Quartic (or 4-fold) factorial numbers: a(n) = Product_{k = 0..n-1} (4*k + 1).

A007696

Quartic (or 4-fold) factorial numbers: a(n) = Product_{k = 0..n-1} (4*k + 1).

Terms

    a(0) =1a(1) =1a(2) =5a(3) =45a(4) =585a(5) =9945a(6) =208845a(7) =5221125a(8) =151412625a(9) =4996616625a(10) =184874815125

External references