a(n) = n*(n + 1)*(n + 2)*(7*n - 5)/12.

Terms

a(0) =0a(1) =1a(2) =18a(3) =80a(4) =230a(5) =525a(6) =1036a(7) =1848a(8) =3060a(9) =4785a(10) =7150a(11) =10296a(12) =14378a(13) =19565a(14) =26040a(15) =34000a(16) =43656a(17) =55233a(18) =68970a(19) =85120a(20) =103950a(21) =125741a(22) =150788a(23) =179400a(24) =211900a(25) =248625a(26) =289926a(27) =336168a(28) =387730a(29) =445005