- Développement décimal périodique de l’inverse d’un nombre premier
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La période du développement décimal périodique d’un nombre rationnel est le cycle composé d’une séquence finie de chiffres qui se répète à l’infini.
L'inverse d'un nombre premier, noté 1/p possède un développement décimal périodique dont la longueur de la période est notée δ(p)
Ceci exclut les nombres premiers 2 et 5 dont l'inverse ne possède pas de développement décimal périodique
Exemple :
1/7 = 0,142857 142857 142857...
δ(7) = 6
Sommaire
Classement des nombres premiers
Le tableau ci-dessous propose un classement des nombres premiers en fonction de la longueur de la période de leurs inverses.
Tableau des nombres premiers dont δp <101
1 3 2 11 3 37 4 101 5 41 271 6 7 13 7 239 4649 8 73 137 9 333667 10 9091 11 21649 513239 12 9901 13 53 79 265371653 14 909091 15 31 2906161 16 17 5882353 17 2071723 5363222357 18 19 52579 19 1111111111111111111 20 3541 27961 21 43 1933 10838689 22 23 4093 8779 23 11111111111111111111111 24 99990001 25 21401 25601 182521213001 26 859 1058313049 27 757 440334654777631 28 29 281 121499449 29 3191 16763 43037 62003 77843839397 30 211 241 2161 31 2791 6943319 57336415063790604359 32 353 449 641 1409 69857 33 67 1344628210313298373 34 103 4013 21993833369 35 71 123551 102598800232111471 36 999999000001 37 2028119 247629013 2212394296770203368013 38 909090909090909091 39 900900900900990990990991 40 1676321 5964848081 41 83 1231 538987 201763709900322803748657942361 42 127 2689 459691 43 173 1527791 1963506722254397 2140992015395526641 44 89 1052788969 1056689261 45 238681 4185502830133110721 46 47 139 2531 549797184491917 47 35121409 316362908763458525001406154038726382279 48 9999999900000001 49 505885997 1976730144598190963568023014679333 50 251 5051 78875943472201 51 613 210631 52986961 13168164561429877 52 521 265371653 1900381976777332243781 53 107 1659431 1325815267337711173 47198858799491425660200071 54 70541929 14175966169 55 1321 62921 83251631 1300635692678058358830121 56 7841 127522001020150503761 57 21319 10749631 3931123022305129377976519 58 59 154083204930662557781201849 59 2559647034361 4340876285657460212144534289928559826755746751 60 61 4188901 39526741 61 733 4637 329401 974293 1360682471 106007173861643 7061709990156159479 62 909090909090909090909090909091 63 10837 23311 45613 45121231 1921436048294281 64 19841 976193 6187457 834427406578561 65 162503518711 5538396997364024056286510640780600481 66 599144041 183411838171 67 493121 79863595778924342083 28213380943176667001263153660999177245677 68 28559389 1491383821 2324557465671829 69 277 203864078068831 1595352086329224644348978893 70 4147571 265212793249617641 71 241573142393627673576957439049 45994811347886846310221728895223034301839 72 3169 98641 3199044596370769 73 12171337159 1855193842151350117 49207341634646326934001739482502131487446637 74 7253 422650073734453 296557347313446299 75 151 4201 15763985553739191709164170940063151 76 722817036322379041 1369778187490592461 77 5237 42043 29920507 136614668576002329371496447555915740910181043 78 157 6397 216451 1058313049 388847808493 79 317 6163 10271 307627 49172195536083790769 3660574762725521461527140564875080461079917 80 5070721 19721061166646717498359681 81 163 9397 2462401 676421558270641 130654897808007778425046117 82 2670502781396266997 3404193829806058997303 83 3367147378267 9512538508624154373682136329 346895716385857804544741137394505425384477 84 226549 4458192223320340849 85 262533041 8119594779271 4222100119405530170179331190291488789678081 86 57009401 2182600451 7306116556571817748755241 87 4003 72559 310170251658029759045157793237339498342763245483 88 617 16205834846012967584927082656402106953 89 497867 103733951 104984505733 5078554966026315671444089 403513310222809053284932818475878953159 90 29611 3762091 8985695684401 91 547 14197 17837 4262077 43442141653 316877365766624209 110742186470530054291318013 92 1289 18371524594609 4181003300071669867932658901 93 900900900900900900900900900900990990990990990990990990990991 94 6299 4855067598095567 297262705009139006771611927 95 191 59281 63841 1289981231950849543985493631 965194617121640791456070347951751 96 97 206209 66554101249 75118313082913 97 12004721 846035731396919233767211537899097169 109399846855370537540339266842070119107662296580348039 98 197 5076141624365532994918781726395939035533 99 199 397 34849 362853724342990469324766235474268869786311886053883 100 60101 7019801 182521213001 14103673319201 78875943472201 1680588011350901 Factorisation de 1 + 10 + 102 + ... + 10n
Soit N1=1, N2=11, N3=111, ..., Nk= = 1 + 10 + 102 + 103 + ... + 10k-1
La factorisation de Nk peut se décomposer comme le produit de P x K x F[1] ou
- P : produit des nombres premiers p dont δp=k
- K : produit des nombres premiers p dont δp est un diviseur de k
- F : produits des nombres pq ou p est un nombre premier et q un exposant >0 tel que :
- pq soit un diviseur de k
- k ≥ δ p x p
- calculé pour k<101
Exemple pour k=6 :Factorisation de 111111 (1+10+102+103+104+105)
- P = 7 x 13
- K = 11 x 37
- K = 3
111111 = 7 x 13 x 11 x 37 x 3
Exemple pour k = 78 :Factorisation de 111111111111111111111111111111111111111111111111111111111111111111111111111111
- P = 157 x 6397 x 216451 x 1058313049 x 388847808493
- K = 11x37x7x13x53x79x265371653x859x1058313049x900900900900990990990991
- K = 3 x 13
Calcul des facteurs K et F
k Diviseur de k Equivalent en nombre premier p (δ(p) est un diviseur de k) Coef. F 1 2 3 3 4 2 11 5 6 2-3 11x37 3 7 8 2-4 11x101 9 3 37 32 10 2-5 11x41x271 11 12 2-3-4-6 11x37x101x7x13 3 13 14 2-7 11x239x4649 15 3-5 37x41x271 3 16 2-4-8 11x101x73x137 17 18 2-3-6-9 11x37x7x13 32 19 20 2-4-5-10 11x101x41x271x9091 21 3-7 37x239x4649 3 22 2-11 11x21649x513239 11 23 24 2-3-4-6-8-12 11x37x101x7x13 3 25 5 41x271 26 2-13 11x53x79x265371653 27 3-9 37x333667 33 28 2-4-7-14 11x101x239x4649x909091 29 30 2-3-5-6-10-15 11x37x41x271x7x13x9091x31x2906161 3 31 32 2-4-8-16 11x101x73x137x17x5882353 33 3-11 37x21649x513239 3 34 2-17 11x2071723x5363222357 35 5-7 41x271x239x4649 36 2-3-4-6-9-12-18 11x37x101x7x13x333667x9901x19x52579 32 37 38 2-19 11x1111111111111111111 39 3-13 37x53x79x265371653 3 40 2-4-5-8-10-20 11x101x41x271x73x137x9091x3541x27961 41 42 2-3-6-7-14-21 11x37x7x13x239x4649x909091x43x1933x10838689 3X7 43 44 2-4-11-22 11x101x21649x513239x23x4093x8779 11 45 3-5-9-15 37x41x271x333667x31x2906161 32 46 2-23 11x11111111111111111111111 47 48 2-3-4-6-8-12-16-24 11x37x101x7x13x73x137x9901x17x5882353x99990001 3 49 7 239x4649 50 2-5-10-25 11x41x271x9091x21401x25601x182521213001 51 3-17 37x2071723x5363222357 3 52 2-4-13-26 11x101x53x79x265371653x859x1058313049 53 54 2-3-9-27 11x37x333667x757x440334654777631 33 55 5-11 41x271x21649x513239 56 2-4-7-8-14-28 11x101x239x4649x73x137x909091x29x281x121499449 57 3-19 37x1111111111111111111 3 58 2-29 11x3191x16763x43037x62003x77843839397 59 60 2-3-4-5-6-10-12-15-20-30 11x37x101x41x271x7x13x9091x9901x31x2906161x3541x27961x211x241x2161 3 61 62 2-31 11x2791x6943319x57336415063790604359 63 3-7-9-21 37x239x4649x333667x43x1933x10838689 32 64 2-4-8-16-32 11x101x73x137x17x5882353x353x449x641x1409x69857 65 5-13 41x271x9901 66 2-3-6-11-22-33 11x37x7x13x21649x513239x23x4093x8779x67x1344628210313298373 3X11 67 68 2-4-17-34 11x101x207123x5363222357x103x4013x21993833369 69 3-23 37x11111111111111111111111 3 70 2-5-7-10-14-35 11x41x271x239x4649x9091x909091x71x123551x102598800232111471 71 72 2-3-4-6-8-9-12-18-24-36 11x37x101x7x13x73x137x333667x9901x19x52579x99990001x999999000001 32 73 74 2-37 1x2028119x247629013x2212394296770203368013 75 3-5-15-25 37X41X271X31X2906161X99990001 3 76 2-4-19-38 11x101x1111111111111111111x909090909090909091 77 7-11 239x4649x21649x513239 78 2-3-6-13-26-39 11x37x7x13x53x79x265371653x859x1058313049x900900900900990990990991 3X13 79 80 2-4-5-8-10-16-20-40 11X101X41X271X73X137X9091X17X5882353X3541X27961X1676321X5964848081 81 3-9-27 37x333667x757x440334654777631 34 82 2-41 11x83x1231x538987x201763709900322803748657942361 83 84 2-3-4-6-7-12-14-21-28-42 11x37x101x7x13x239x4649x9901x909091x43x1933x10838689x29x281x121499449x127x2689x459691 3*7 85 5-17 41x271x2071723x5363222357 86 2-43 11x173x1527791x1963506722254397x2140992015395526641 87 3-29 37x3191x16763x43037x62003x77843839397 3 88 2-4-8-11-22-44 11x101x73x137x21649x513239x23x4093x8779x89x1052788969x1056689261 11 89 90 2-3-5-6-9-10-15-18-30-45 11x37x41x271x7x13x333667x9091x31x2906161x19x52579x211x241x2161x238681x4185502830133110721 3 91 7-13 239x4649x53x79x265371653 92 2-4-23-46 11x101x11111111111111111111111x47x139x2531x549797184491917 93 3-31 37x2791x6943319x57336415063790604359 3 94 2-47 11x35121409x316362908763458525001406154038726382279 95 5-19 41x271x1111111111111111111 96 2-3-4-6-8-12-16-24-32-48 11x37x101x7x13x73x137x9901x17x5882353x99990001x353x449x641x1409x69857x9999999900000001 3 97 98 2-7-14-49 11x239x4649x909091x505885997x1976730144598190963568023014679333 99 3-9-11-33 37x333667x21649x513239x67x1344628210313298373 3 100 2-4-5-10-20-25-50 11x101x41x271x9091x3541x27961x21401x25601x182521213001
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