An Euler triangle.

Terms

a(0) =1a(1) =0a(2) =1a(3) =0a(4) =4a(5) =1a(6) =0a(7) =48a(8) =12a(9) =1a(10) =0a(11) =1088a(12) =272a(13) =24a(14) =1a(15) =0a(16) =39680a(17) =9920a(18) =880a(19) =40a(20) =1a(21) =0a(22) =2122752a(23) =530688a(24) =47104a(25) =2160a(26) =60a(27) =1a(28) =0a(29) =156577792