a(n) = (n-1)*(n-2)*(n+3)*(n+2)/12.

Terms

a(0) =1a(1) =0a(2) =0a(3) =5a(4) =21a(5) =56a(6) =120a(7) =225a(8) =385a(9) =616a(10) =936a(11) =1365a(12) =1925a(13) =2640a(14) =3536a(15) =4641a(16) =5985a(17) =7600a(18) =9520a(19) =11781a(20) =14421a(21) =17480a(22) =21000a(23) =25025a(24) =29601a(25) =34776a(26) =40600a(27) =47125a(28) =54405a(29) =62496