A square array of quadratic-factorial numbers, read by antidiagonals.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =2a(6) =1a(7) =7a(8) =14a(9) =6a(10) =1a(11) =13a(12) =42a(13) =78a(14) =24a(15) =1a(16) =21a(17) =86a(18) =258a(19) =504a(20) =120a(21) =1a(22) =31a(23) =146a(24) =546a(25) =1752a(26) =3720a(27) =720a(28) =1a(29) =43