Sequence whose G.f is given by: 1/(1-z)/(1-2*z)^2/(1-z-z^2).

Terms

a(0) =1a(1) =6a(2) =24a(3) =79a(4) =232a(5) =632a(6) =1633a(7) =4058a(8) =9788a(9) =23063a(10) =53332a(11) =121452a(12) =273089a(13) =607534a(14) =1339376a(15) =2929951a(16) =6366480a(17) =13752880a(18) =29556545a(19) =63232370a(20) =134731956a(21) =286044711a(22) =605326044a(23) =1277246724a(24) =2687879137a(25) =5642847462a(26) =11820387528a(27) =24710992303