Numbers k such that k and k^2 use only the digits 0, 2, 5 and 6.

Terms

a(0) =0a(1) =5a(2) =25a(3) =50a(4) =225a(5) =250a(6) =255a(7) =500a(8) =505a(9) =2250a(10) =2500a(11) =2550a(12) =5000a(13) =5005a(14) =5025a(15) =5050a(16) =22500a(17) =25000a(18) =25005a(19) =25025a(20) =25500a(21) =25505a(22) =50000a(23) =50005a(24) =50025a(25) =50050a(26) =50225a(27) =50250a(28) =50255a(29) =50500