G.f. satisfies A(x) = ( 1 + x * (A(x)^(1/3) / (1-x))^(3/2) )^3.

Terms

a(0) =1a(1) =3a(2) =12a(3) =46a(4) =174a(5) =654a(6) =2451a(7) =9177a(8) =34368a(9) =128826a(10) =483531a(11) =1817673a(12) =6844294a(13) =25815660a(14) =97539435a(15) =369154485a(16) =1399419360a(17) =5313440610a(18) =20205330660a(19) =76946898744a(20) =293443125804