a(n) = n*(n + 1)*(n + 2)*(4*n - 3)/6.

Terms

a(0) =0a(1) =1a(2) =20a(3) =90a(4) =260a(5) =595a(6) =1176a(7) =2100a(8) =3480a(9) =5445a(10) =8140a(11) =11726a(12) =16380a(13) =22295a(14) =29680a(15) =38760a(16) =49776a(17) =62985a(18) =78660a(19) =97090a(20) =118580a(21) =143451a(22) =172040a(23) =204700a(24) =241800a(25) =283725a(26) =330876a(27) =383670a(28) =442540a(29) =507935