A007318 * A143097.

Terms

a(0) =1a(1) =3a(2) =9a(3) =22a(4) =50a(5) =113a(6) =256a(7) =576a(8) =1281a(9) =2818a(10) =6146a(11) =13313a(12) =28672a(13) =61440a(14) =131073a(15) =278530a(16) =589826a(17) =1245185a(18) =2621440a(19) =5505024a(20) =11534337a(21) =24117250a(22) =50331650a(23) =104857601a(24) =218103808a(25) =452984832a(26) =939524097a(27) =1946157058a(28) =4026531842a(29) =8321499137