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

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =7a(5) =1a(6) =2a(7) =43a(8) =43a(9) =2a(10) =3a(11) =277a(12) =969a(13) =277a(14) =3a(15) =5a(16) =1777a(17) =23663a(18) =23663a(19) =1777a(20) =5a(21) =8a(22) =11407a(23) =571099a(24) =2180738a(25) =571099a(26) =11407a(27) =8a(28) =13a(29) =73219