Numbers k such that k and k^2 use only the digits 0, 2, 3, 4 and 7.

Terms

a(0) =0a(1) =2a(2) =20a(3) =200a(4) =2000a(5) =20000a(6) =200000a(7) =2000000a(8) =4740332a(9) =20000000a(10) =27204302a(11) =47403320a(12) =200000000a(13) =272043020a(14) =474033200a(15) =2000000000a(16) =2702734302a(17) =2720430200a(18) =4477474032a(19) =4740332000a(20) =20000000000a(21) =27027343020a(22) =27204302000a(23) =44774740320a(24) =47227474032a(25) =47403320000a(26) =200000000000a(27) =270273430200a(28) =272043020000a(29) =447747403200