A049640 a(n)=Sum{T(i,n-i): i=0,1,...,n), array T as in A049639.

0, 0, 2, 4, 7, 10, 15, 20, 27, 34, 45, 56, 69, 82, 101, 120, 143, 166, 195, 224, 257, 290, 333, 376, 423, 470, 529, 588, 653, 718, 791, 864, 945, 1026, 1123, 1220, 1323, 1426, 1547, 1668, 1797