G.f. A(x) satisfies A(x) = 1 + Sum_{n>=1} A(x)^n * x^n*(1 + x^n)^n.

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =23a(5) =71a(6) =245a(7) =844a(8) =3031a(9) =11023a(10) =40890a(11) =153456a(12) =582868a(13) =2234096a(14) =8634800a(15) =33607223a(16) =131619098a(17) =518285703a(18) =2050849866a(19) =8150520122a(20) =32519072805a(21) =130205541912a(22) =523022475545