G.f.: Sum_{n>=0} x^n * Product_{k=1..n} (k + (n-k+1)*x) / (1 + k*x + (n-k+1)*x^2).

A363110

G.f.: Sum_{n>=0} x^n * Product_{k=1..n} (k + (n-k+1)*x) / (1 + k*x + (n-k+1)*x^2).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =28a(6) =88a(7) =306a(8) =1158a(9) =4730a(10) =20722a(11) =96776a(12) =479340a(13) =2507510a(14) =13804014a(15) =79718782a(16) =481614806a(17) =3036358968a(18) =19932689952a(19) =135981543762a(20) =962319171782

External references