Numbers k such that k and k^2 use only the digits 2, 3, 4, 5 and 7.

Terms

a(0) =2a(1) =5a(2) =235a(3) =2335a(4) =7235a(5) =23335a(6) =72335a(7) =233335a(8) =477235a(9) =2333335a(10) =2354235a(11) =23333335a(12) =47354235a(13) =233333335a(14) =235744235a(15) =273372335a(16) =274477235a(17) =473732335a(18) =723432335a(19) =2333333335a(20) =2333524235a(21) =2733723335a(22) =4747354235a(23) =7372744235a(24) =23333333335a(25) =23333524235a(26) =27472254235a(27) =52224777235a(28) =57223732335a(29) =72334323335