Array read by antidiagonals: T(m,n) = number of (undirected) paths in the grid graph P_m X P_n.

Terms

a(0) =0a(1) =1a(2) =1a(3) =3a(4) =12a(5) =3a(6) =6a(7) =49a(8) =49a(9) =6a(10) =10a(11) =146a(12) =322a(13) =146a(14) =10a(15) =15a(16) =373a(17) =1618a(18) =1618a(19) =373a(20) =15a(21) =21a(22) =872a(23) =7119a(24) =14248a(25) =7119a(26) =872a(27) =21a(28) =28a(29) =1929