Triangular sequence from a Pidduck polynomials expansion: p(t) = (t/(1 - t))*((1 + t)/(1 - t))^x.

Terms

a(0) =1a(1) =2a(2) =4a(3) =6a(4) =12a(5) =12a(6) =24a(7) =64a(8) =48a(9) =32a(10) =120a(11) =320a(12) =400a(13) =160a(14) =80a(15) =720a(16) =2208a(17) =2400a(18) =1920a(19) =480a(20) =192a(21) =5040a(22) =15456a(23) =21952a(24) =13440a(25) =7840a(26) =1344a(27) =448a(28) =40320a(29) =135168