A158036 Integer solutions f for f = (4^n - 2^n + 8n^2 - 2) / (2n * (2n + 1)) with n an integer

3, 8287, 32547981403, 3374074914839397834392750148706282243018046503, 107547872626305931371847778721098686654377801057464206176785452350259573207, 4568366860875634575966528292411682488942909674818941246717098803707597353756388768388059303363024343431

Offset

1,1

Comments

8287 = 129 * 64 + 31 = 257 * 32 + 63 is prime. A158034 (values of n) is often prime. A158035 (2n + 1) appears to be always prime.

See A235540 for nonprimes in A158034. - Reinhard Zumkeller, Nov 17 2014

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..32

Prog

 (Haskell)
a158036 = (\x -> (4^x - 2^x + 8*x^2 - 2) `div` (2*x*(2*x + 1))) . a158034
-- Reinhard Zumkeller, Nov 17 2014

Crossrefs

Cf. A158034, A158035 (n, 2n + 1)

Cf. A002515 (Lucasian primes)

Cf. A145918 (exponential Sophie Germain primes)

Cf. A235540.

Sequence in context: A068918 A356645 A362124 * A242865 A280300 A171363

Adjacent sequences: A158033 A158034 A158035 * A158037 A158038 A158039

Keyword

nonn

Author

Reikku Kulon, Mar 11 2009

Status

approved