Triangle of the number of alternating sign matrices according to the number of -1's.

Terms

a(0) =1a(1) =2a(2) =6a(3) =1a(4) =24a(5) =16a(6) =2a(7) =120a(8) =200a(9) =94a(10) =14a(11) =1a(12) =720a(13) =2400a(14) =2684a(15) =1284a(16) =310a(17) =36a(18) =2a(19) =5040a(20) =29400a(21) =63308a(22) =66158a(23) =38390a(24) =13037a(25) =2660a(26) =328a(27) =26a(28) =1