Numbers k such that k and k^2 use only the digits 1, 2, 3, 4 and 9.

Terms

a(0) =1a(1) =2a(2) =3a(3) =11a(4) =12a(5) =21a(6) =111a(7) =139a(8) =212a(9) =339a(10) =1111a(11) =1193a(12) =4943a(13) =11132a(14) =12212a(15) =14139a(16) =14943a(17) =21193a(18) =43923a(19) =49229a(20) =119132a(21) =122193a(22) =141111a(23) =149139a(24) =221911a(25) =439229a(26) =492239a(27) =499423a(28) =1192193a(29) =1221193