a(n) = Bernoulli(2n)*(2n+1)!/n!.

A168136

a(n) = Bernoulli(2n)*(2n+1)!/n!.

Terms

    a(0) =1a(1) =1a(2) =-2a(3) =20a(4) =-504a(5) =25200a(6) =-2189088a(7) =302702400a(8) =-62564261760

External references