A puzzle array read by antidiagonals.

Terms

a(0) =1a(1) =2a(2) =1a(3) =3a(4) =3a(5) =1a(6) =4a(7) =9a(8) =4a(9) =1a(10) =5a(11) =21a(12) =31a(13) =5a(14) =1a(15) =6a(16) =41a(17) =220a(18) =129a(19) =6a(20) =1a(21) =7a(22) =71a(23) =1081a(24) =6949a(25) =651a(26) =7a(27) =1a(28) =8a(29) =113