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.

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A058046 Numbers k such that 5^k - k is prime.

Original entry on oeis.org

2, 6, 12, 362, 884, 9722
Offset: 1

Views

Author

Robert G. Wilson v, Nov 17 2000

Keywords

Comments

Farideh Firoozbakht reports that the only known prime of the form 5^k + k occurs when k = 7954 and that there are no others up to 20200. Oct 11 2003. [See A382786. - Michael S. Branicky, May 02 2025]
a(7) > 2*10^5. - Robert Price, Jan 16 2014

Crossrefs

Cf. A382786.

Programs

  • Mathematica
    Do[ If[ PrimeQ[ 5^n - n ], Print[ n ] ], {n, 1, 13400} ]
  • PARI
    is(n)=ispseudoprime(5^n-n) \\ Charles R Greathouse IV, Feb 20 2017

Extensions

The sixth term was found by Farideh Firoozbakht, who reports that there are no others up to 13400, Oct 11 2003
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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