Riordan array (c(2x)^2,xc(2x)), c(x) the g.f. of A000108.

Terms

a(0) =1a(1) =4a(2) =1a(3) =20a(4) =6a(5) =1a(6) =112a(7) =36a(8) =8a(9) =1a(10) =672a(11) =224a(12) =56a(13) =10a(14) =1a(15) =4224a(16) =1440a(17) =384a(18) =80a(19) =12a(20) =1a(21) =27456a(22) =9504a(23) =2640a(24) =600a(25) =108a(26) =14a(27) =1a(28) =183040a(29) =64064