Even pentagonal pyramidal numbers.

Terms

a(0) =0a(1) =6a(2) =18a(3) =40a(4) =126a(5) =196a(6) =288a(7) =550a(8) =726a(9) =936a(10) =1470a(11) =1800a(12) =2176a(13) =3078a(14) =3610a(15) =4200a(16) =5566a(17) =6348a(18) =7200a(19) =9126a(20) =10206a(21) =11368a(22) =13950a(23) =15376a(24) =16896a(25) =20230a(26) =22050a(27) =23976a(28) =28158a(29) =30420