a(n) = n*(n + 5)*(n + 10)/6.

Terms

a(0) =0a(1) =11a(2) =28a(3) =52a(4) =84a(5) =125a(6) =176a(7) =238a(8) =312a(9) =399a(10) =500a(11) =616a(12) =748a(13) =897a(14) =1064a(15) =1250a(16) =1456a(17) =1683a(18) =1932a(19) =2204a(20) =2500a(21) =2821a(22) =3168a(23) =3542a(24) =3944a(25) =4375a(26) =4836a(27) =5328a(28) =5852a(29) =6409