a(n) = n*(n + 1)*(4*n + 5)/2.

Terms

a(0) =0a(1) =9a(2) =39a(3) =102a(4) =210a(5) =375a(6) =609a(7) =924a(8) =1332a(9) =1845a(10) =2475a(11) =3234a(12) =4134a(13) =5187a(14) =6405a(15) =7800a(16) =9384a(17) =11169a(18) =13167a(19) =15390a(20) =17850a(21) =20559a(22) =23529a(23) =26772a(24) =30300a(25) =34125a(26) =38259a(27) =42714a(28) =47502a(29) =52635