a(n) = 972*n^2 - 270*n (n>=1).

Terms

a(0) =702a(1) =3348a(2) =7938a(3) =14472a(4) =22950a(5) =33372a(6) =45738a(7) =60048a(8) =76302a(9) =94500a(10) =114642a(11) =136728a(12) =160758a(13) =186732a(14) =214650a(15) =244512a(16) =276318a(17) =310068a(18) =345762a(19) =383400a(20) =422982a(21) =464508a(22) =507978a(23) =553392a(24) =600750a(25) =650052a(26) =701298a(27) =754488a(28) =809622a(29) =866700