a(n) = (2^n-1)^2*(2^n + 2).

Terms

a(0) =0a(1) =4a(2) =54a(3) =490a(4) =4050a(5) =32674a(6) =261954a(7) =2096770a(8) =16776450a(9) =134216194a(10) =1073738754a(11) =8589928450a(12) =68719464450a(13) =549755789314