Square array read by antidiagonals arising in the enumeration of corners.

Terms

a(0) =1a(1) =2a(2) =2a(3) =5a(4) =16a(5) =5a(6) =14a(7) =91a(8) =91a(9) =14a(10) =42a(11) =456a(12) =936a(13) =456a(14) =42a(15) =132a(16) =2145a(17) =7425a(18) =7425a(19) =2145a(20) =132a(21) =429a(22) =9724a(23) =50765a(24) =85800a(25) =50765a(26) =9724a(27) =429a(28) =1430a(29) =43043