a(n) = 6*n*(9*n-5).

Terms

a(0) =0a(1) =24a(2) =156a(3) =396a(4) =744a(5) =1200a(6) =1764a(7) =2436a(8) =3216a(9) =4104a(10) =5100a(11) =6204a(12) =7416a(13) =8736a(14) =10164a(15) =11700a(16) =13344a(17) =15096a(18) =16956a(19) =18924a(20) =21000a(21) =23184a(22) =25476a(23) =27876a(24) =30384a(25) =33000a(26) =35724a(27) =38556a(28) =41496a(29) =44544