Riordan array (1/(1-x*c(3*x)), x*c(3*x)/(1-x*c(3*x))), c(x) the g.f. of A000108.

Terms

a(0) =1a(1) =1a(2) =1a(3) =4a(4) =5a(5) =1a(6) =25a(7) =33a(8) =9a(9) =1a(10) =190a(11) =256a(12) =78a(13) =13a(14) =1a(15) =1606a(16) =2186a(17) =703a(18) =139a(19) =17a(20) =1a(21) =14506a(22) =19863a(23) =6591a(24) =1430a(25) =216a(26) =21a(27) =1a(28) =137089a(29) =188449