Array read by antidiagonals, generated by the matrix M = [1,1,1;1,N,1;1,1,1].

Terms

a(0) =1a(1) =1a(2) =3a(3) =1a(4) =3a(5) =8a(6) =1a(7) =3a(8) =9a(9) =22a(10) =1a(11) =3a(12) =10a(13) =27a(14) =60a(15) =1a(16) =3a(17) =11a(18) =34a(19) =81a(20) =164a(21) =1a(22) =3a(23) =12a(24) =43a(25) =116a(26) =243a(27) =448a(28) =1a(29) =3