Number triangle associated to the Riordan arrays (1/(1+x),x/(1+x)^k),k>=0.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =2a(5) =2a(6) =1a(7) =2a(8) =4a(9) =2a(10) =1a(11) =2a(12) =6a(13) =8a(14) =2a(15) =1a(16) =2a(17) =8a(18) =20a(19) =16a(20) =2a(21) =1a(22) =2a(23) =10a(24) =38a(25) =70a(26) =32a(27) =2a(28) =1a(29) =2