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

Terms

a(0) =1a(1) =1a(2) =4a(3) =14a(4) =40a(5) =102a(6) =244a(7) =562a(8) =1264a(9) =2798a(10) =6124a(11) =13290a(12) =28648a(13) =61414a(14) =131044a(15) =278498a(16) =589792a(17) =1245150a(18) =2621404a(19) =5504986a(20) =11534296a(21) =24117206a(22) =50331604a(23) =104857554a(24) =218103760a(25) =452984782a(26) =939524044a(27) =1946157002a(28) =4026531784a(29) =8321499078