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

Terms

a(0) =1a(1) =5a(2) =20a(3) =75a(4) =279a(5) =1040a(6) =3881a(7) =14485a(8) =54060a(9) =201755a(10) =752959a(11) =2810080a(12) =10487361a(13) =39139365a(14) =146070100a(15) =545141035a(16) =2034494039a(17) =7592835120a(18) =28336846441a(19) =105754550645a(20) =394681356140