183092554714domain: NAppears in sequencesNumerator of s_{2n}, where s_0 = 1, s_n = | 2^n*(2^(n-1)-1)*Bernoulli(n)/n! | for n>0.at n=10A171078a(n) = B2(n) * C(n) where B2(n) are generalized Bernoulli numbers and C(n) the Clausen numbers.at n=20A225480