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 A304980 a(n) = 4^n * (1 - 4^n) * Bernoulli(2*n) / (2*n) + EulerE(2*n). 0

%I

%S -2,7,-77,1657,-58457,3056557,-221729237,21295269457,-2614745018417,

%T 399460073350357,-74300372446261997,16529958050063939257,

%U -4333993989483331875977,1322511243007573825356157,-464663077436832702395156357,186233354336664458732835601057

%N a(n) = 4^n * (1 - 4^n) * Bernoulli(2*n) / (2*n) + EulerE(2*n).

%F a(n) = (-1)^n * (A000182(n) + A000364(n)).

%t Array[4^#*(1 - 4^#) BernoulliB[2 #]/(2 #) + EulerE[2 #] &, 16] (* _Michael De Vlieger_, May 24 2018 *)

%o (PARI) a(n) = 4^n * (1 - 4^n) * bernfrac(2*n) / (2*n) + 2*imag(polylog(-2*n, I)); \\ _Michel Marcus_, May 30 2018

%Y Cf. A000367 (Bernoulli numerators), A002445 (Bernoulli denominators), A028296 (EulerE(2*n)), A241242.

%Y Cf. A000182 (tangent numbers), A000364 (secant numbers).

%K sign

%O 1,1

%A _Daniel Suteu_, May 22 2018

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Last modified June 6 17:28 EDT 2020. Contains 334830 sequences. (Running on oeis4.)