cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A178194 Smallest k such that 33^k mod k = n.

Original entry on oeis.org

1, 2, 31, 5, 29, 7, 21, 13, 13684967, 10, 23, 14, 15, 538, 19, 42, 17, 35, 25, 49, 16861, 60, 55, 26, 1157, 38, 511, 54, 30197665, 106, 14691, 46, 155, 37, 18791, 62, 369, 164, 145, 93, 63517, 92, 115, 1046, 3113077, 58, 1376107, 1042, 105, 50, 221
Offset: 0

Views

Author

Artur Jasinski, May 22 2010

Keywords

Comments

smallest k such that m^k mod k = n
m=2 see A036236
m=3 see A078457
m=4 see A119678
m=5 see A119679
m=6 see A127816
m=7 see A119715
m=8 see A119714
m=9 see A127817
m=10 see A127818
m=11 see A127819
m=12 see A127820
m=13 see A127821
m=14 see A128154
m=15 see A128155
m=16 see A128156
m=17 see A128157
m=18 see A128158
m=19 see A128159
m=20 see A128160
m=21 see A128361
m=22 see A128362
m=23 see A128363
m=24 see A128364
m=25 see A128365
m=26 see A128366
m=27 see A128367
m=28 see A128368
m=29 see A128369
m=30 see A128370
m=31 see A128371
m=32 see A128372
m=33 see A178194
m=34 see A178195
m=35 see A178196
m=36 see A178197
m=37 see A178198
m=38 see A178199
m=39 see A178200
m=40 see A178201
m=41 see A178202

Crossrefs

see comment line.

Programs

  • Mathematica
    aa = {}; Do[k = 1; While[PowerMod[33, k, k] != n, k++ ]; Print[k]; AppendTo[aa, k], {n, 0, 50}]; aa

A178202 Smallest k such that 41^k mod k = n.

Original entry on oeis.org

1, 2, 3, 19, 37, 76, 7, 17, 9, 22, 31, 15, 29, 77, 309, 34, 7194589, 26, 23, 341, 21, 55, 799, 1658, 476983, 46, 27, 427, 629, 52, 142241, 138, 68889, 136, 1897, 129, 30935, 44, 19303, 1642, 34943, 43, 8858994648397, 102, 117, 436, 7715, 86, 49
Offset: 0

Views

Author

Artur Jasinski, May 23 2010

Keywords

Crossrefs

Programs

  • Mathematica
    aa = {}; Do[k = 1; While[PowerMod[41, k, k] != n, k++ ]; Print[{n, k}]; AppendTo[aa, k], {n, 1, 50}]; aa

Extensions

a(0)=1 prepended and a(42) added by Max Alekseyev, Feb 04 2012

A124977 Least positive number k such that 2^k mod k = 2n+1, or 0 if no such k exists.

Original entry on oeis.org

0, 4700063497, 19147, 25, 2228071, 262279, 95, 481, 45, 2873, 3175999, 555, 95921, 174934013, 777, 140039, 2463240427, 477, 91, 623, 2453, 55, 345119, 1131, 943, 21967, 135, 46979, 125, 3811, 23329, 155, 1064959, 245
Offset: 0

Views

Author

Zak Seidov, Nov 14 2006

Keywords

Examples

			a(3) = 25 because 2^25 = 33554432 = 7 + 25*1342177.
		

Crossrefs

Programs

  • Mathematica
    nk[n_] := Module[ {k}, k = 1;
      While[PowerMod[2, k, k] != 2 n + 1, k++]; k]
    Join[{0}, Table[nk[i], {i, 1, 33}]]  (* Robert Price, Oct 11 2018 *)

Formula

A bisection of A036236: a(n) = A036236(2n+1).

Extensions

Edited by Max Alekseyev, May 20 2011

A128125 Numbers k such that 2^k == 14 (mod k).

Original entry on oeis.org

1, 2, 3, 10, 1010, 61610, 469730, 2037190, 3820821, 9227438, 21728810, 24372562, 207034456857, 1957657325241, 2002159320610, 35169368880130, 36496347203230, 116800477091426
Offset: 1

Views

Author

Alexander Adamchuk, Feb 15 2007

Keywords

Comments

No other terms below 10^15. Some larger terms: 279283702428813463, 3075304070192893442, 21894426987819404424310, 4616079845508388554313022889, 82759461944940747300611642693066719359651817521, 446*(2^445-7)/1061319625781480182060453906975 (107 digits). - Max Alekseyev, Oct 03 2016

Crossrefs

Cf. A015910, A036236, A050259 (numbers k such that 2^k == 3 (mod k)), A033981, A051447, A033982, A051446, A033983, A128121, A128122, A128123, A128124, A128126.

Programs

  • Mathematica
    For[n=1, n<= 10^6, n++, If[PowerMod[2,n,n] == Mod[14,n], Print[n]]] (* Stefan Steinerberger, May 05 2007 *)
    m = 14; Join[Select[Range[m], Divisible[2^# - m, #] &],
    Select[Range[m + 1, 10^6], PowerMod[2, #, #] == m &]] (* Robert Price, Oct 08 2018 *)

Extensions

1, 2, 3 and 10 added by N. J. A. Sloane, Apr 23 2007
More terms from Stefan Steinerberger, May 05 2007
a(13) from Max Alekseyev, May 15 2011
a(14), a(16), a(17) from Max Alekseyev, Dec 16 2013
a(15), a(18) from Max Alekseyev, Oct 03 2016

A128370 a(n) = least k such that the remainder of 30^k divided by k is n.

Original entry on oeis.org

29, 7, 26997, 13, 8471, 33, 23, 11, 721, 55, 19, 39, 17, 886, 21, 26, 803, 98, 13289, 22, 51, 878, 1141, 146, 35, 38, 111, 218, 515267673651961, 31, 3212679202339, 56, 267, 866, 4367, 42, 10129, 862, 57, 86, 42691, 13479, 949, 214, 95, 77, 7633, 52, 1469, 170, 429, 68, 2791229, 94, 215, 422, 3849, 842, 9773, 140
Offset: 1

Views

Author

Alexander Adamchuk, Feb 27 2007

Keywords

Crossrefs

Programs

  • Mathematica
    t = Table[0, {10000} ]; k = 1; While[ k < 5100000000, a = PowerMod[30, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t (* Robert G. Wilson v, Aug 06 2009 *)

Extensions

Terms a(29) onward from Max Alekseyev, Mar 22 2012

A129492 Composite numbers k such that 2^k mod k is a power of 2.

Original entry on oeis.org

6, 9, 10, 12, 14, 15, 20, 21, 22, 24, 26, 28, 30, 33, 34, 38, 39, 40, 44, 46, 48, 51, 52, 56, 57, 58, 60, 62, 63, 65, 66, 68, 69, 72, 74, 76, 78, 80, 82, 84, 85, 86, 87, 90, 92, 93, 94, 96, 102, 106, 111, 112, 114, 116, 118, 120, 122, 123, 124, 126, 129, 132, 133, 134, 138
Offset: 1

Views

Author

Robert G. Wilson v, Apr 17 2007

Keywords

Comments

Complement to composite numbers: 4, 8, 16, 18, 25, 27, 32, 35, 36, 42, 45, 49, 50, 54, 55, 64, 70, 75, 77, 81, 88, 91, 95, 98, 99, ....

Examples

			15 is a term since 2^15 mod 15 = 8.
		

Crossrefs

Programs

  • Magma
    [k:k in [2..150]| not IsPrime(k)  and  not IsZero(a)  and (PrimeDivisors(a) eq [2]) where a is 2^k mod k ]; // Marius A. Burtea, Dec 04 2019
  • Maple
    filter:= proc(n) local k;
      if isprime(n) then return false fi;
      k:= 2 &^ n mod n;
      k > 1 and k = 2^padic:-ordp(k,2)
    end proc:
    select(filter, [$4..1000]); # Robert Israel, Dec 03 2019
  • Mathematica
    Select[Range@ 141, IntegerQ@ Log[2, PowerMod[2, #, # ]] &]

A129493 Composite numbers k such that 3^k mod k is a power of 3.

Original entry on oeis.org

6, 10, 12, 14, 18, 22, 24, 26, 30, 33, 34, 36, 38, 39, 46, 51, 54, 56, 57, 58, 62, 63, 66, 69, 72, 74, 78, 82, 86, 87, 90, 91, 92, 93, 94, 99, 104, 106, 108, 111, 112, 116, 117, 118, 120, 121, 122, 123, 124, 129, 132, 134, 135, 141, 142, 144, 146, 148, 154, 158, 159
Offset: 1

Views

Author

Robert G. Wilson v, Apr 17 2007

Keywords

Comments

Complement to composite numbers: 9, 15, 21, 25, 27, 28, 35, 42, 44, 45, 48, 49, 50, 52, 55, 60, 65, 68, 70, 75, ....

Examples

			14 is a member of the sequence since 3^14 mod 14 = 9.
		

Crossrefs

Programs

  • Magma
    [k:k in [2..160]| not IsPrime(k)  and  not IsZero(a)  and (PrimeDivisors(a) eq [3]) where a is 3^k mod k ]; // Marius A. Burtea, Dec 04 2019
  • Maple
    filter:= proc(n) local k;
      if isprime(n) then return false fi;
      k:= 3 &^ n mod n;
      k > 1 and k = 3^padic:-ordp(k,3)
    end proc:
    select(filter, [$4..1000]); # Robert Israel, Dec 03 2019
  • Mathematica
    Select[Range@ 161, IntegerQ@ Log[3, PowerMod[3, #, # ]] &]

A129494 Composite numbers k such that 4^k mod k is a power of 4 greater than 1.

Original entry on oeis.org

6, 12, 15, 20, 22, 24, 26, 28, 30, 34, 38, 40, 46, 48, 56, 58, 60, 62, 66, 69, 72, 74, 77, 80, 82, 84, 85, 86, 87, 88, 91, 93, 94, 96, 102, 104, 105, 106, 111, 117, 118, 120, 122, 123, 126, 129, 132, 134, 140, 141, 142, 144, 146, 158, 159, 166, 168, 170, 177, 178, 182
Offset: 1

Views

Author

Robert G. Wilson v, Apr 17 2007

Keywords

Comments

Complement to composite numbers: 4, 8, 9, 10, 14, 16, 18, 21, 25, 27, 32, 33, 35, 36, 39, 42, 44, 45, 49, 50, 51, 52, 54, 55, 57, ... - R. J. Mathar, May 16 2008

Examples

			22 is a term since 4^22 mod 22 = 16.
		

Crossrefs

Contains A122781 except for 1 and 4.

Programs

  • Magma
    [k:k in [2..200]| not IsPrime(k)  and  not IsZero(a)  and (PrimeDivisors(a) eq [2]) and  &+[j[1]*j[2]: j in Factorization(a) ] mod 4 eq 0 where a is 4^k mod k]; // Marius A. Burtea, Dec 04 2019
  • Maple
    filter:= proc(n) local k,j;
      if isprime(n) then return false fi;
      k:= 4 &^ n mod n;
      j:= padic:-ordp(k,2);
      k>1 and j::even and k = 2^j
    end proc:
    select(filter, [$4..1000]); # Robert Israel, Dec 03 2019
  • Mathematica
    Select[ Range@ 161, IntegerQ@ Log[4, PowerMod[4, #, # ]] &]

Extensions

Corrected and extended by R. J. Mathar, May 16 2008

A129495 Composite numbers k such that 5^k (mod k) is a power of 5 greater than 1.

Original entry on oeis.org

10, 15, 20, 26, 30, 34, 38, 40, 46, 50, 56, 58, 60, 62, 65, 74, 78, 82, 86, 94, 100, 106, 118, 120, 122, 124, 129, 130, 132, 134, 140, 141, 142, 143, 146, 150, 155, 158, 159, 166, 177, 178, 182, 183, 190, 194, 195, 200, 201, 202, 206, 213, 214, 217, 218, 219
Offset: 1

Views

Author

Robert G. Wilson v, Apr 17 2007

Keywords

Examples

			26 is a member of the sequence since 5^26 (mod 26) == 25.
		

Crossrefs

Programs

  • Mathematica
    Select[Range@ 225, (p = PowerMod[5, #, #]) > 1 && IntegerQ@ Log[5, p] && CompositeQ[#] &] (* corrected by Amiram Eldar, Jul 24 2021 *)

A129496 Composite numbers k such that 6^k (mod k) is a power of 6 greater than 1.

Original entry on oeis.org

10, 15, 21, 30, 35, 38, 42, 45, 46, 58, 60, 62, 70, 74, 82, 84, 86, 90, 94, 105, 106, 118, 122, 126, 132, 134, 140, 142, 146, 158, 166, 178, 180, 182, 185, 190, 194, 202, 206, 210, 214, 215, 217, 218, 219, 222, 226, 228, 231, 237, 249, 252, 254, 258, 259, 262
Offset: 1

Views

Author

Robert G. Wilson v, Apr 17 2007

Keywords

Examples

			38 is a member of the sequence since 6^38 (mod 38) == 36.
		

Crossrefs

Programs

  • Mathematica
    Select[Range@ 266, (p = PowerMod[6, #, #]) > 1 && IntegerQ@ Log[6, p] && CompositeQ[#] &] (* corrected by Amiram Eldar, Jul 24 2021 *)
Previous Showing 41-50 of 67 results. Next