a(n) = 10*binomial(n,2) + 9*n.

Terms

a(0) =0a(1) =9a(2) =28a(3) =57a(4) =96a(5) =145a(6) =204a(7) =273a(8) =352a(9) =441a(10) =540a(11) =649a(12) =768a(13) =897a(14) =1036a(15) =1185a(16) =1344a(17) =1513a(18) =1692a(19) =1881a(20) =2080a(21) =2289a(22) =2508a(23) =2737a(24) =2976a(25) =3225a(26) =3484a(27) =3753a(28) =4032a(29) =4321