A007318 * A000203.

Terms

a(0) =1a(1) =4a(2) =11a(3) =29a(4) =71a(5) =168a(6) =389a(7) =884a(8) =1978a(9) =4375a(10) =9592a(11) =20874a(12) =45124a(13) =96979a(14) =207402a(15) =441724a(16) =937393a(17) =1982767a(18) =4181349a(19) =8793756a(20) =18448907a(21) =38620883a(22) =80690867a(23) =168285817a(24) =350383797a(25) =728381793a(26) =1511953441a(27) =3134224224a(28) =6489055959a(29) =13419472021