Numbers k such that k and k^2 use only the digits 2, 5, 6, 7 and 9.

Terms

a(0) =5a(1) =25a(2) =26a(3) =27a(4) =75a(5) =76a(6) =77a(7) =275a(8) =277a(9) =525a(10) =526a(11) =527a(12) =725a(13) =976a(14) =2565a(15) =7227a(16) =7275a(17) =7525a(18) =7527a(19) =7565a(20) =7725a(21) =22925a(22) =25676a(23) =27525a(24) =52227a(25) =52725a(26) =72565a(27) =72576a(28) =75277a(29) =97765