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 A097350 Numbers n such that (Sum (2k)^k, k=1..n) - 1 is prime. 1
 2, 3, 6, 49 (list; graph; refs; listen; history; text; internal format)
 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 (rpropper(AT)stanford.edu), Aug 23 2005 LINKS 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 * A062309 A018390 A180615 Adjacent sequences:  A097347 A097348 A097349 * A097351 A097352 A097353 KEYWORD nonn AUTHOR Rick L. Shepherd, Aug 07 2004 STATUS approved

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