a(n) = the least integer that is polygonal in exactly n ways.

Terms

a(0) =3a(1) =6a(2) =15a(3) =36a(4) =225a(5) =561a(6) =1225a(7) =11935a(8) =11781a(9) =27405a(10) =220780a(11) =203841a(12) =3368925a(13) =4921840a(14) =7316001a(15) =33631521a(16) =142629201a(17) =879207616a(18) =1383958576a(19) =3800798001a(20) =12524486976a(21) =181285005825a(22) =118037679760a(23) =239764947345a(24) =738541591425