The On-Line Encyclopedia of Integer Sequences (OEIS)

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A097350

Numbers n such that (Sum (2k)^k, k=1..n) - 1 is prime.
(history; published version)

#5 by Charles R Greathouse IV at Wed Oct 02 15:12:41 EDT 2013

COMMENTS

Term 49 corresponds to a certified prime (Primo 2.2.0 beta). Next term is greater than 5400. - _Ryan Propper (rpropper(AT)stanford.edu), _, Aug 23 2005

Discussion

Wed Oct 02

15:12

OEIS Server: https://oeis.org/edit/global/1961

#4 by Russ Cox at Fri Mar 30 17:36:43 EDT 2012

AUTHOR

_Rick L. Shepherd (rshepherd2(AT)hotmail.com), _, Aug 07 2004

Discussion

Fri Mar 30

17:36

OEIS Server: https://oeis.org/edit/global/176

#3 by N. J. A. Sloane at Sun Jun 29 03:00:00 EDT 2008

COMMENTS

The term 49 is associated with a Some of the larger entries may only correspond to probable prime. Any additional terms are greater than 830primes.

KEYWORD

nonn,new

nonn

#2 by N. J. A. Sloane at Wed Sep 21 03:00:00 EDT 2005

OFFSET

0,1,1

COMMENTS

Term 49 corresponds to a certified prime (Primo 2.2.0 beta). Next term is greater than 5400. - Ryan Propper (rpropper(AT)stanford.edu), Aug 23 2005

KEYWORD

more,nonn,new

nonn

#1 by N. J. A. Sloane at Wed Sep 22 03:00:00 EDT 2004

NAME

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

DATA

2, 3, 6, 49

OFFSET

0,1

COMMENTS

The term 49 is associated with a probable prime. Any additional terms are greater than 830.

EXAMPLE

6 is a term as 2^1 + 4^2 + 6^3 + 8^4 + 10^5 + 12^6 - 1 = 3090313, which is prime.

PROG

(PARI) s=-1; for(k=1, 830, s=s+(2*k)^k; if(isprime(s), print1(k, ", ")))

CROSSREFS

Cf. A073825 (Sum k^k, k=1..n, is prime), A097349 ((Sum (2k)^k, k=1..n) + 1 is prime).

KEYWORD

more,nonn

AUTHOR

Rick L. Shepherd (rshepherd2(AT)hotmail.com), Aug 07 2004

STATUS

approved