a(n) = 324*n^2 - 804*n + 468 (n>=2).

Terms

a(0) =156a(1) =972a(2) =2436a(3) =4548a(4) =7308a(5) =10716a(6) =14772a(7) =19476a(8) =24828a(9) =30828a(10) =37476a(11) =44772a(12) =52716a(13) =61308a(14) =70548a(15) =80436a(16) =90972a(17) =102156a(18) =113988a(19) =126468a(20) =139596a(21) =153372a(22) =167796a(23) =182868a(24) =198588a(25) =214956a(26) =231972a(27) =249636a(28) =267948a(29) =286908