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 1-2 of 2 results.

A212378 Primes congruent to 1 mod 61.

Original entry on oeis.org

367, 733, 977, 1709, 1831, 2441, 3539, 4027, 4271, 4637, 4759, 5003, 5857, 6101, 6833, 7321, 7687, 8053, 8297, 8419, 8663, 9029, 9151, 9883, 10859, 12323, 12689, 13177, 13421, 14153, 14519, 15373, 15739, 16349, 17203, 17569, 18301, 18911, 21107, 21839, 21961
Offset: 1

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Author

Bruno Berselli, Sep 20 2012

Keywords

Comments

Coincides for the first 58 terms with A059230, that is the sequence of primes p such that x^61 = 2 has no solution mod p (first divergence is at 34039).

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(22000) | IsOne(p mod 61)];
    
  • Mathematica
    Select[Prime[Range[2500]], Mod[#, 61] == 1 &]
    Select[Range[1, 22000, 61], PrimeQ]
  • PARI
    is(n)=isprime(n) && n%61==1 \\ Charles R Greathouse IV, Jul 03 2016

Formula

a(n) ~ 60n log n. - Charles R Greathouse IV, Jul 03 2016

A216884 Primes p such that x^61 = 2 has a solution mod p.

Original entry on oeis.org

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271
Offset: 1

Views

Author

Vincenzo Librandi, Sep 19 2012

Keywords

Comments

Complement of A059230 relative to A000040.
Naturally this sequence is not the same as A000040. First disagreement at index 73: a(73)=373, A000040(73)=367. [Bruno Berselli, Sep 20 2012]

Programs

  • Magma
    [p: p in PrimesUpTo(500) | exists(t){x: x in ResidueClassRing(p) | x^61 eq 2}];
  • Mathematica
    ok[p_] := Reduce[Mod[x^61 - 2, p] == 0, x, Integers] == True; Select[Prime[Range[150]], ok]
Showing 1-2 of 2 results.