a(n) = (4*n+9)(!^4)/9(!^4), related to A007696(n+1) ((4*n+1)(!^4) quartic, or 4-factorials).

A051621

a(n) = (4*n+9)(!^4)/9(!^4), related to A007696(n+1) ((4*n+1)(!^4) quartic, or 4-factorials).

Terms

    a(0) =1a(1) =13a(2) =221a(3) =4641a(4) =116025a(5) =3364725a(6) =111035925a(7) =4108329225a(8) =168441498225

External references