Squares of odd pentagonal numbers.

Terms

a(0) =1a(1) =25a(2) =1225a(3) =2601a(4) =13689a(5) =21025a(6) =61009a(7) =82369a(8) =180625a(9) =227529a(10) =423801a(11) =511225a(12) =855625a(13) =1002001a(14) =1555009a(15) =1782225a(16) =2614689a(17) =2948089a(18) =4141225a(19) =4609609a(20) =6255001a(21) =6890625a(22) =9090225a(23) =9928801a(24) =12794929a(25) =13875625a(26) =17530969a(27) =18896409a(28) =23474025a(29) =25170289