a(n)=Sum(C(n,2k+1)5^k 3^(2k+1) 7^(n-2k-1), k=0,..,Floor[(n-1)/2]).

A097068

a(n)=Sum(C(n,2k+1)5^k 3^(2k+1) 7^(n-2k-1), k=0,..,Floor[(n-1)/2]).

Terms

    a(0) =0a(1) =3a(2) =42a(3) =576a(4) =7896a(5) =108240a(6) =1483776a(7) =20339904a(8) =278823552a(9) =3822170112a(10) =52395087360a(11) =718242542592

External references