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a(n) = (nextprime(4^n) - nextprime(2^n))/2.
1

%I #11 Dec 09 2020 20:47:49

%S 0,1,6,28,120,497,2016,8140,32640,130813,523776,2096133,8386580,

%T 33550335,134209524,536854528,2147450887,8589869054,34359607310,

%U 137438691321,549755289604,2199022206975,8796090925052,35184367894531,140737479966709,562949936644106

%N a(n) = (nextprime(4^n) - nextprime(2^n))/2.

%F a(n) = A037130(n) / 2. - _Sean A. Irvine_, Dec 09 2020

%t Table[(NextPrime[4^n]-NextPrime[2^n])/2,{n,0,30}] (* _Harvey P. Dale_, May 26 2011 *)

%K nonn

%O 0,3

%A _N. J. A. Sloane_.

%E More terms from _Sean A. Irvine_, Dec 09 2020