G.f.: Sum_{k>=0} A000041(k)^3 * x^k / Sum_{k>=0} A000009(k) * x^k.

Terms

a(0) =1a(1) =0a(2) =7a(3) =18a(4) =98a(5) =210a(6) =969a(7) =1938a(8) =7037a(9) =15258a(10) =44815a(11) =93180a(12) =262391a(13) =518550a(14) =1311015a(15) =2657328a(16) =6189160a(17) =12124098a(18) =27239760a(19) =52063668a(20) =111630480a(21) =211503288a(22) =432900236a(23) =806091180a(24) =1610854427a(25) =2940167268a(26) =5691072911a(27) =10289144976a(28) =19402974147a(29) =34523231688