a(n) = (2^(n+4)-1)*(2^n-1).

Terms

a(0) =0a(1) =31a(2) =189a(3) =889a(4) =3825a(5) =15841a(6) =64449a(7) =259969a(8) =1044225a(9) =4185601a(10) =16759809a(11) =67074049a(12) =268365825a(13) =1073602561a(14) =4294688769a(15) =17179312129a(16) =68718362625a(17) =274875678721