a(n) = (-1)^n*Product_{k=1..n} (2*k + 1)*(2*k - 3).

A380612

a(n) = (-1)^n*Product_{k=1..n} (2*k + 1)*(2*k - 3).

Terms

    a(0) =1a(1) =3a(2) =-15a(3) =315a(4) =-14175a(5) =1091475a(6) =-127702575a(7) =21070924875

External references