a(n) = n*(19*n + 1)/2.

Terms

a(0) =0a(1) =10a(2) =39a(3) =87a(4) =154a(5) =240a(6) =345a(7) =469a(8) =612a(9) =774a(10) =955a(11) =1155a(12) =1374a(13) =1612a(14) =1869a(15) =2145a(16) =2440a(17) =2754a(18) =3087a(19) =3439a(20) =3810a(21) =4200a(22) =4609a(23) =5037a(24) =5484a(25) =5950a(26) =6435a(27) =6939a(28) =7462a(29) =8004