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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A097349 Numbers n such that (Sum (2k)^k, k=1..n) + 1 is prime.

Original entry on oeis.org

1, 2, 13, 72, 318, 13583
Offset: 1

Views

Author

Rick L. Shepherd, Aug 07 2004

Keywords

Comments

Some of the larger entries may only correspond to probable primes.
The numbers produced by 72 and 318 have now been certified prime by Primo. 13583, found by PrimeForm using recurrence mode, corresponds to a 60228-digit probable prime. - Rick L. Shepherd, Apr 29 2006

Examples

			13 is a term as 2^1 + 4^2 + 6^3 + 8^4 + 10^5 + 12^6 + 14^7 + 16^8 + 18^9 + 20^10 + 22^11 + 24^12 + 26^13 + 1 = 2518267981703965963, which is prime (certified with Primo).

Crossrefs

Cf. A073825 (Sum k^k, k=1..n, is prime), A097350 ((Sum (2k)^k, k=1..n) - 1 is prime).

Programs

  • PARI
    s=1; for(k=1,700, s=s+(2*k)^k; if(isprime(s), print1(k,",")))

Extensions

One more term from Rick L. Shepherd, Apr 29 2006
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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