Triangle of self-avoiding rook paths joining opposite corners of n X k board.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =4a(5) =12a(6) =1a(7) =8a(8) =38a(9) =184a(10) =1a(11) =16a(12) =125a(13) =976a(14) =8512a(15) =1a(16) =32a(17) =414a(18) =5382a(19) =79384a(20) =1262816a(21) =1a(22) =64a(23) =1369a(24) =29739a(25) =752061a(26) =20562673a(27) =575780564a(28) =1a(29) =128