a(n) = 2^n*(n^3 - 3*n^2 + 2*n + 48)/48.

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =24a(5) =72a(6) =224a(7) =688a(8) =2048a(9) =5888a(10) =16384a(11) =44288a(12) =116736a(13) =301056a(14) =761856a(15) =1896448a(16) =4653056a(17) =11272192a(18) =27000832a(19) =64028672a(20) =150470656a(21) =350748672a(22) =811597824a(23) =1865416704a(24) =4261412864a(25) =9680453632a(26) =21877489664a(27) =49207574528a(28) =110192754688a(29) =245752659968