p-INVERT of the quarter-squares (A002620), where p(S) = 1 - S - S^2.

Terms

a(0) =1a(1) =4a(2) =15a(3) =53a(4) =185a(5) =643a(6) =2234a(7) =7764a(8) =26988a(9) =93819a(10) =326149a(11) =1133811a(12) =3941521a(13) =13702079a(14) =47633109a(15) =165588965a(16) =575643853a(17) =2001134880a(18) =6956629199a(19) =24183622175a(20) =84070541130a(21) =292257951771