Irregular triangle read by rows: T(n,k) = number of k-irredundant sets in the n X n rook graph.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =4a(5) =6a(6) =1a(7) =9a(8) =36a(9) =48a(10) =1a(11) =16a(12) =120a(13) =416a(14) =632a(15) =1a(16) =25a(17) =300a(18) =1900a(19) =6550a(20) =10930a(21) =400a(22) =1a(23) =36a(24) =630a(25) =6240a(26) =37080a(27) =128592a(28) =240192a(29) =39600