Indices of 9-gonal numbers that are also square.

Terms

a(0) =1a(1) =2a(2) =18a(3) =49a(4) =529a(5) =1458a(6) =15842a(7) =43681a(8) =474721a(9) =1308962a(10) =14225778a(11) =39225169a(12) =426298609a(13) =1175446098a(14) =12774732482a(15) =35224157761a(16) =382815675841