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Integer solutions f for f = (4^n - 2^n + 8n^2 - 2) / (2n * (2n + 1)) with n an integer.
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%I #10 Jun 24 2024 22:27:23

%S 3,8287,32547981403,3374074914839397834392750148706282243018046503,

%T 107547872626305931371847778721098686654377801057464206176785452350259573207,

%U 4568366860875634575966528292411682488942909674818941246717098803707597353756388768388059303363024343431

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

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

%C See A235540 for nonprimes in A158034. - _Reinhard Zumkeller_, Nov 17 2014

%H Reinhard Zumkeller, <a href="/A158036/b158036.txt">Table of n, a(n) for n = 1..32</a>

%o (Haskell)

%o a158036 = (\x -> (4^x - 2^x + 8*x^2 - 2) `div` (2*x*(2*x + 1))) . a158034

%o -- _Reinhard Zumkeller_, Nov 17 2014

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

%Y Cf. A002515 (Lucasian primes)

%Y Cf. A145918 (exponential Sophie Germain primes)

%Y Cf. A235540.

%K nonn

%O 1,1

%A _Reikku Kulon_, Mar 11 2009