p-INVERT of the positive integers, where p(S) = 1 - S - S^2 - S^3 + S^4.

Terms

a(0) =1a(1) =4a(2) =15a(3) =54a(4) =188a(5) =645a(6) =2208a(7) =7570a(8) =25982a(9) =89190a(10) =306095a(11) =1050268a(12) =3603276a(13) =12361763a(14) =42409154a(15) =145491117a(16) =499126660a(17) =1712311759a(18) =5874263702a(19) =20152234481a(20) =69134134820a(21) =237171010852a(22) =813636681973