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.

A268987 Primes of the form k^(k + 1) + k - 1.

Original entry on oeis.org

83, 15629, 279941, 3486784409, 6568408355712890639
Offset: 1

Views

Author

Soumadeep Ghosh, Feb 16 2016

Keywords

Comments

The next prime has 171 digits. - Vincenzo Librandi, Feb 17 2016
Subsequence of primes of A155499. - Michel Marcus, Feb 20 2016

Crossrefs

Cf. A309140 (the corresponding values of k).

Programs

  • Magma
    [a: n in [0..100] | IsPrime(a) where a is n^(n+1)+n-1]; // Vincenzo Librandi, Feb 17 2016
    
  • Mathematica
    Select[Table[n^(n + 1) + n - 1, {n, 1, 50}], ProvablePrimeQ[#] &]
  • PARI
    lista(nn) = for(k=1, nn, if(ispseudoprime(q=k^(k+1)+k-1), print1(q, ", "))); \\ Jinyuan Wang, Mar 01 2020

A309140 Numbers k such that k^(k + 1) + k - 1 is prime.

Original entry on oeis.org

3, 5, 6, 9, 15, 87, 2323, 13733
Offset: 1

Views

Author

Hugo Pfoertner, Jul 23 2019

Keywords

Comments

a(7) > 2000.
a(8) > 5000. - Daniel Suteu, Jul 25 2019
a(8) > 10000. - Michael S. Branicky, Apr 01 2023

Crossrefs

Programs

  • PARI
    for(n=1,100,my(x=n^(n+1)+n-1);if(isprime(x),print1(n,", ")))

Extensions

a(7) from Daniel Suteu, Jul 25 2019
a(8) from Michael S. Branicky, Nov 04 2024
Showing 1-2 of 2 results.