Even 14-gonal (or tetradecagonal) numbers.

Terms

a(0) =0a(1) =14a(2) =76a(3) =186a(4) =344a(5) =550a(6) =804a(7) =1106a(8) =1456a(9) =1854a(10) =2300a(11) =2794a(12) =3336a(13) =3926a(14) =4564a(15) =5250a(16) =5984a(17) =6766a(18) =7596a(19) =8474a(20) =9400a(21) =10374a(22) =11396a(23) =12466a(24) =13584a(25) =14750a(26) =15964a(27) =17226a(28) =18536a(29) =19894