a(n) = (2*n-1)*(5*n^2-5*n+6)/6.

Terms

a(0) =1a(1) =8a(2) =30a(3) =77a(4) =159a(5) =286a(6) =468a(7) =715a(8) =1037a(9) =1444a(10) =1946a(11) =2553a(12) =3275a(13) =4122a(14) =5104a(15) =6231a(16) =7513a(17) =8960a(18) =10582a(19) =12389a(20) =14391a(21) =16598a(22) =19020a(23) =21667a(24) =24549a(25) =27676a(26) =31058a(27) =34705a(28) =38627a(29) =42834