E.g.f.: Product_{m >= 1} (1+x^(2*m)/(2*m)) (even powers only).

A087639

E.g.f.: Product_{m >= 1} (1+x^(2*m)/(2*m)) (even powers only).

Terms

    a(0) =1a(1) =1a(2) =6a(3) =210a(4) =8400a(5) =740880a(6) =88814880a(7) =15217282080

External references