a(n) = (-1)^(n+1)/5 * Sum_{k=1..2n} binomial(2n+1,k)*B(k)*5^k where B(k) are the Bernoulli numbers.

A069990

a(n) = (-1)^(n+1)/5 * Sum_{k=1..2n} binomial(2n+1,k)*B(k)*5^k where B(k) are the Bernoulli numbers.

Terms

    a(0) =1a(1) =15a(2) =389a(3) =17687a(4) =1230957a(5) =121576879a(6) =16166877205

External references