Pentagonal triangle.

Terms

a(0) =1a(1) =6a(2) =12a(3) =18a(4) =57a(5) =51a(6) =40a(7) =156a(8) =209a(9) =145a(10) =75a(11) =330a(12) =531a(13) =534a(14) =330a(15) =126a(16) =600a(17) =1074a(18) =1278a(19) =1122a(20) =651a(21) =196a(22) =987a(23) =1895a(24) =2488a(25) =2559a(26) =2081a(27) =1162a(28) =288a(29) =1512