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%I #20 Nov 18 2017 13:13:42
%S 1,2,8,64,128,1024,2830336,32768,118521856,11499470848,183092903936,
%T 651652235264,3965531409350656,88306004000768,1821484971735384064,
%U 7400951301593676906496,16555640873195841519616,2604961188466481168384
%N Denominator of (-1)^(n+1) * (2*n)! * (2^(2*n)+1)/(B_{2*n} * 2^(4*n-1)), where B_{n} is the Bernoulli number.
%C Pi^(2*n) > A295231(n)/a(n) for n > 0.
%H Seiichi Manyama, <a href="/A295232/b295232.txt">Table of n, a(n) for n = 0..275</a>
%e Zeta(2) = Pi^2/6 > 1 + 1/2^2, so Pi^2 > 15/2.
%e Zeta(4) = Pi^4/90 > 1 + 1/2^4, so Pi^4 > 765/8.
%e Zeta(6) = Pi^6/945 > 1 + 1/2^6, so Pi^6 > 61425/64.
%o (PARI) {a(n) = denominator((-1)^(n+1)*(2*n)!*(2^(2*n)+1)/(bernfrac(2*n)*2^(4*n-1)))}
%Y Cf. A002432/A046988, A295231 (numerators).
%K nonn,frac
%O 0,2
%A _Seiichi Manyama_, Nov 18 2017
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