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A097350
Numbers n such that (Sum (2k)^k, k=1..n) - 1 is prime.
1
OFFSET
1,1
COMMENTS
Some of the larger entries may only correspond to probable primes.
Term 49 corresponds to a certified prime (Primo 2.2.0 beta). Next term is greater than 5400. - Ryan Propper, Aug 23 2005
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).
Sequence in context: A049383 A099411 A018372 * A323721 A277374 A062309
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Aug 07 2004
STATUS
approved