a(n) = Sum_{i=0..n} T(i,n-i), array T as in A049747.

Terms

a(0) =0a(1) =4a(2) =9a(3) =20a(4) =37a(5) =66a(6) =101a(7) =148a(8) =209a(9) =294a(10) =383a(11) =512a(12) =639a(13) =814a(14) =1003a(15) =1224a(16) =1461a(17) =1750a(18) =2047a(19) =2420a(20) =2791a(21) =3206a(22) =3661a(23) =4176a(24) =4731a(25) =5354a(26) =5977a(27) =6688a(28) =7429a(29) =8250