a(n) = (3*n^2 - 3*n + 8)*2^(n - 3).

Terms

a(0) =1a(1) =2a(2) =7a(3) =26a(4) =88a(5) =272a(6) =784a(7) =2144a(8) =5632a(9) =14336a(10) =35584a(11) =86528a(12) =206848a(13) =487424a(14) =1134592a(15) =2613248a(16) =5963776a(17) =13500416a(18) =30343168a(19) =67764224a(20) =150470656a(21) =332398592a(22) =730857472a(23) =1600126976a(24) =3489660928a(25) =7583301632a(26) =16424894464a(27) =35467034624a(28) =76369887232a(29) =164014063616