Number of isosceles right triangles on a 2n X (n+1) grid.

Terms

a(0) =4a(1) =50a(2) =208a(3) =582a(4) =1308a(5) =2556a(6) =4528a(7) =7460a(8) =11620a(9) =17310a(10) =24864a(11) =34650a(12) =47068a(13) =62552a(14) =81568a(15) =104616a(16) =132228a(17) =164970a(18) =203440a(19) =248270a(20) =300124a(21) =359700a(22) =427728a(23) =504972a(24) =592228a(25) =690326a(26) =800128a(27) =922530a(28) =1058460a(29) =1208880