Antidiagonal triangle sequence based on recursion: f(n,a)=a*f(n-1,a)+n*f(n-2,a).

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =1a(5) =1a(6) =0a(7) =1a(8) =2a(9) =4a(10) =0a(11) =1a(12) =3a(13) =7a(14) =8a(15) =0a(16) =1a(17) =4a(18) =12a(19) =22a(20) =28a(21) =0a(22) =1a(23) =5a(24) =19a(25) =48a(26) =79a(27) =76a(28) =0a(29) =1