a(n) = (n+1)^2*(n+2)*(2*n+3)/6.

Terms

a(0) =1a(1) =10a(2) =42a(3) =120a(4) =275a(5) =546a(6) =980a(7) =1632a(8) =2565a(9) =3850a(10) =5566a(11) =7800a(12) =10647a(13) =14210a(14) =18600a(15) =23936a(16) =30345a(17) =37962a(18) =46930a(19) =57400a(20) =69531a(21) =83490a(22) =99452a(23) =117600a(24) =138125a(25) =161226a(26) =187110a(27) =215992a(28) =248095a(29) =283650