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.

Showing 1-4 of 4 results.

A059264 Primes p such that x^12 = 2 has no solution mod p.

Original entry on oeis.org

3, 5, 7, 11, 13, 17, 19, 29, 37, 41, 43, 53, 59, 61, 67, 73, 79, 83, 97, 101, 103, 107, 109, 131, 137, 139, 149, 151, 157, 163, 173, 179, 181, 193, 197, 199, 211, 227, 229, 241, 251, 269, 271, 277, 283, 293, 307, 313, 317, 331, 337, 347, 349, 367, 373, 379, 389
Offset: 1

Views

Author

Klaus Brockhaus, Jan 23 2001

Keywords

Comments

Complement of A049544 relative to A000040.
Coincides for the first 119 terms with sequence of primes p such that x^36 = 2 has no solution mod p (first divergence is at 919, cf. A059668).

Crossrefs

Programs

  • Mathematica
    ok[p_] := Reduce[Mod[x^12 - 2, p] == 0, x, Integers] == False; Select[Prime[Range[100]],ok] (* Vincenzo Librandi, Sep 14 2012 *)
    Select[ Prime@ Range@ PrimePi@400, !MemberQ[ PowerMod[ Range@#, 12, #], Mod[2, #]] &] (* Robert G. Wilson v, Nov 05 2016 after Bruno Berselli in A059362 *)

A049556 Primes p such that x^24 = 2 has a solution mod p.

Original entry on oeis.org

2, 23, 31, 47, 71, 89, 127, 167, 191, 223, 233, 239, 257, 263, 311, 359, 383, 431, 439, 479, 503, 599, 601, 647, 719, 727, 743, 839, 863, 881, 887, 911, 919, 983, 1031, 1103, 1151, 1217, 1223, 1289, 1319, 1327, 1367, 1399, 1423, 1433, 1439, 1471, 1487, 1511
Offset: 1

Views

Author

Keywords

Comments

Complement of A059362 relative to A000040. - Vincenzo Librandi, Sep 14 2012

Examples

			0^24 == 2 (mod 2). 5^24 == 2 (mod 23). 3^24 == 2 (mod 31). 2^24 == 2 (mod 47). 24^24 == 2 (mod 71). 25^24 == 2 (mod 89). 5^24 == 2 (mod 127). 63^24 == 2 (mod 167). - _R. J. Mathar_, Jul 20 2025
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(1600) | exists(t){x : x in ResidueClassRing(p) | x^24 eq 2}]; // Vincenzo Librandi, Sep 14 2012
  • Mathematica
    ok[p_]:= Reduce[Mod[x^24 - 2, p] == 0, x, Integers] =!= False; Select[Prime[Range[300]], ok] (* Vincenzo Librandi, Sep 14 2012 *)

A212376 Primes p such that x^48 = 2 has no solution mod p.

Original entry on oeis.org

3, 5, 7, 11, 13, 17, 19, 29, 37, 41, 43, 53, 59, 61, 67, 73, 79, 83, 97, 101, 103, 107, 109, 113, 131, 137, 139, 149, 151, 157, 163, 173, 179, 181, 193, 197, 199, 211, 227, 229, 241, 251, 269, 271, 277, 281, 283, 293, 307, 313, 317, 331, 337, 347, 349, 353, 367
Offset: 1

Views

Author

Bruno Berselli, Sep 14 2012

Keywords

Comments

Complement of A049580 relative to A000040.
This sequence is not the same as A059362. First disagreement at index 162: a(162)=1217, A059362(162)=1229.

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(400) | forall{x: x in ResidueClassRing(p) | x^48 ne 2}];
    
  • Mathematica
    Select[Prime[Range[PrimePi[400]]], ! MemberQ[PowerMod[Range[#], 48, #], Mod[2, #]] &]
    ok[p_] := Reduce[Mod[x^48 - 2, p] == 0, x, Integers] == False; Select[Prime[Range[75]], ok] (* Vincenzo Librandi, Sep 21 2012 *)
  • PARI
    N=10^4;  default(primelimit,N);
    ok(p, r, k)={ return ( (p==r) || (Mod(r,p)^((p-1)/gcd(k,p-1))==1) ); }
    forprime(p=2,N, if (! ok(p,2,48),print1(p,", ")));
    /* Joerg Arndt, Sep 21 2012 */

A059669 Primes p such that x^48 = 2 has no solution mod p, but x^24 = 2 has a solution mod p.

Original entry on oeis.org

1217, 1553, 1777, 2833, 4049, 4481, 5297, 6449, 6689, 7121, 8081, 8609, 9137, 9281, 9649, 10337, 10433, 11329, 11633, 12241, 13121, 14321, 14753, 15569, 16433, 16673, 18257, 19793, 23057, 25169, 25889, 26177, 26561, 26993, 27281, 28001, 29153, 29201
Offset: 1

Views

Author

Klaus Brockhaus, Feb 04 2001

Keywords

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(30000) | not exists{x: x in ResidueClassRing(p) | x^48 eq 2} and exists{x: x in ResidueClassRing(p) | x^24 eq 2}]; // Vincenzo Librandi, Sep 21 2012
  • Mathematica
    Select[Prime[Range[PrimePi[30000]]], ! MemberQ[PowerMod[Range[#], 48, #], Mod[2, #]] && MemberQ[PowerMod[Range[#], 24, #], Mod[2, #]] &] (* Vincenzo Librandi, Sep 22 2013 *)

Extensions

a(37)-a(38) from Vincenzo Librandi, Sep 21 2012
Showing 1-4 of 4 results.