A007318 * A157019.

Terms

a(0) =1a(1) =3a(2) =7a(3) =17a(4) =39a(5) =89a(6) =203a(7) =459a(8) =1029a(9) =2299a(10) =5129a(11) =11409a(12) =25273a(13) =55787a(14) =122875a(15) =270239a(16) =593331a(17) =1299883a(18) =2841243a(19) =6197855a(20) =13499235a(21) =29366411a(22) =63809311a(23) =138466835a(24) =300036895a(25) =649186659a(26) =1402796793a(27) =3027908077a(28) =6529611587a(29) =14068804905