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.

A121799 Values of k from A061092.

Original entry on oeis.org

1, 1, 2, 4, 2, 12, 4, 8, 26, 2, 8, 18, 16, 2, 6, 12, 4, 32, 30, 6, 40, 60, 22, 12, 208, 18, 48, 168, 18, 76, 6, 232, 48, 4, 50, 78, 28, 236, 68, 1026, 10, 162, 6, 138, 162, 48, 120, 330, 82, 414, 130, 188, 164, 6, 6, 100, 126, 10, 36, 40, 48, 94, 14, 218, 954
Offset: 1

Views

Author

Zak Seidov, Oct 26 2005, Dec 14 2006

Keywords

Comments

A061092 is: a(0) = 1; for n>0 a(n) is the smallest prime, larger than a(n-1), of the form k*a(n-1) + 1. - Corrected by Zak Seidov, Oct 03 2015

Links

Crossrefs

Cf. A061092, A072532, A113334.

Programs

  • Mathematica
    a = {2}; b = {1}; Do[k = 1; p = a[[n - 1]]; While[! PrimeQ[k p + 1], k++]; AppendTo[a, k p + 1]; AppendTo[b, k], {n, 2, 60}]; b (* Michael De Vlieger, Oct 03 2015, after Robert G. Wilson v at A061092 *)

Formula

a(n) = (A061092(n)-1)/A061092(n-1). - Zak Seidov, Oct 03 2015

Extensions

Definition corrected by Ken Takusagawa, Jan 17 2006
Corrected and extended by T. D. Noe, Mar 10 2007
Edited by N. J. A. Sloane, Aug 08 2008 at the suggestion of R. J. Mathar

A258081 Values of k in A071580.

Original entry on oeis.org

1, 1, 1, 1, 2, 10, 12, 10, 21, 25, 70, 670, 239, 2115, 586, 1619, 26800, 2505, 99019, 40903, 285641, 67166, 1852765
Offset: 1

Views

Author

Andrew R. Booker, May 19 2015

Keywords

Comments

The first 23 terms were found using gwnum, and the first 22 have been independently checked using gmp.

Links

Crossrefs

Cf. A061092, A072532, A113334.

Programs

  • PARI
    terms=12; p=2; for(n=2, terms, q=p+1; while(!ispseudoprime(q), q=q+p); print1(q\p,", "); p=p*q) \\ Serge Batalov, May 19 2015

A113767 Values of the exponents in A084435.

Original entry on oeis.org

0, 1, 2, 1, 5, 1, 1, 29, 3, 37, 31, 227, 835, 115, 7615, 6071, 218431
Offset: 1

Views

Author

Ken Takusagawa, Jan 19 2006

Keywords

Comments

If A084435 ever hits a Sierpinski number, the sequence is finite.
a(18) > 10^6. - Harsh R. Aggarwal, Sep 14 2024

Links

Crossrefs

Cf. A084435, A113334, A121799.

Programs

  • PARI
    a=2;for(x=1,16,for(k=0,1000000,p=2^k*a+1;if(isprime(p),print(k);break));a=p)

Extensions

a(16)-a(17) from Harsh R. Aggarwal, Apr 11 2018
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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