3 times 13-gonal (or tridecagonal) numbers: a(n) = 3*n*(11*n - 9)/2.

Terms

a(0) =0a(1) =3a(2) =39a(3) =108a(4) =210a(5) =345a(6) =513a(7) =714a(8) =948a(9) =1215a(10) =1515a(11) =1848a(12) =2214a(13) =2613a(14) =3045a(15) =3510a(16) =4008a(17) =4539a(18) =5103a(19) =5700a(20) =6330a(21) =6993a(22) =7689a(23) =8418a(24) =9180a(25) =9975a(26) =10803a(27) =11664a(28) =12558a(29) =13485