4*(2n-1)!*H(2n), where H(n) = Sum 1/i are harmonic numbers.

A008380

4*(2n-1)!*H(2n), where H(n) = Sum 1/i are harmonic numbers.

Terms

    a(0) =6a(1) =50a(2) =1176a(3) =54792a(4) =4251456a(5) =495480960a(6) =80990184960

External references