Symmetric array T(n,m) of the number of 2-convex polygons with 2n horizontal and 2m vertical steps, read by antidiagonals.

A157518

Symmetric array T(n,m) of the number of 2-convex polygons with 2n horizontal and 2m vertical steps, read by antidiagonals.

Terms

    a(0) =6a(1) =104a(2) =104a(3) =908a(4) =1818a(5) =908a(6) =5298a(7) =16560a(8) =16560a(9) =5298a(10) =23261a(11) =105510a(12) =158768a(13) =105510a(14) =23261a(15) =82603a(16) =522325a(17) =1086904a(18) =1086904a(19) =522325a(20) =82603a(21) =249245a(22) =2125965a(23) =5916957a(24) =7962500a(25) =5916957a(26) =2125965a(27) =249245a(28) =661751a(29) =7394811

External references