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 1-3 of 3 results.

A271171 Erroneous version of A270798.

Original entry on oeis.org

5081, 5591, 6211, 6271, 8581, 8861, 9011, 9661
Offset: 1

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Comments

The correct first term is 5281, not 5081 as given in [Lehmer].

A001583 Artiads: the primes p == 1 (mod 5) for which Fibonacci((p-1)/5) is divisible by p.

Original entry on oeis.org

211, 281, 421, 461, 521, 691, 881, 991, 1031, 1151, 1511, 1601, 1871, 1951, 2221, 2591, 3001, 3251, 3571, 3851, 4021, 4391, 4441, 4481, 4621, 4651, 4691, 4751, 4871, 5081, 5281, 5381, 5531, 5591, 5641, 5801, 5881, 6011, 6101, 6211, 6271, 6491, 6841
Offset: 1

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Comments

From A.H.M. Smeets, Nov 15 2023: (Start)
Mean gap size between two consecutive terms at p: ~ 20*log(p) (see E. Lehmer).
In E. Lehmer, Artiads characterized, she counted in the table on p. 122 the primes p for which p == 1 (mod 5) instead of all primes. As a result, in the corollary on p. 121, the 20% becomes 5% (or 1/20 instead of 1/5). (End)

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A047650, A000045, A024894, subsequence of A030430.
See also A270798 (a subsequence), A270800.

Programs

  • Haskell
    a001583 n = a001583_list !! (n-1)
    a001583_list = filter
       (\p -> mod (a000045 $ div (p - 1) 5) p == 0) a030430_list
    -- Reinhard Zumkeller, Aug 15 2013
    
  • Mathematica
    Select[ Prime[ Range[1000]], Mod[#, 5] == 1 && Divisible[ Fibonacci[(# - 1)/5], #] &] (* Jean-François Alcover, Jun 22 2012 *)
  • PARI
    fibmod(n, m)=((Mod([1, 1; 1, 0], m))^n)[1, 2]
    list(lim)=my(v=List()); forprime(p=11,lim, if(p%5==1 && fibmod(p\5,p)==0, listput(v,p))); Vec(v) \\ Charles R Greathouse IV, Feb 06 2017

Formula

From A.H.M. Smeets, Nov 15 2023: (Start)
Equals {prime(m): A296240(m) == 0 (mod 5)}.
a(n) ~ prime(20*n). (End)

Extensions

More terms from James Sellers, Jan 25 2000
Edited by N. J. A. Sloane, Apr 01 2016

A271210 Artiads (A001583) congruent to 1 mod 50 and for which 5 is a quintic residue.

Original entry on oeis.org

13451, 15901, 19001, 19801, 21701, 22901, 28001, 38851, 50551, 64301, 65101, 66851, 78101, 89101, 94351, 95701, 96401, 117751, 124001, 126001, 127951, 136601, 138401, 150301, 162251, 164701, 167051, 178301, 178501, 181001, 183301, 185051, 185401, 185951, 186301
Offset: 1

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Author

Eric M. Schmidt, Apr 02 2016

Keywords

Comments

Hyperartiads (A270798) congruent to 1 mod 50.

Crossrefs

Programs

  • Sage
    def isa(n) : return n % 50 == 1 and is_prime(n) and 5.powermod((n-1)//5, n) == 1 and fibonacci((n - 1)//5) % n == 0
Showing 1-3 of 3 results.