

A136884


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


1



0, 2, 20, 200, 2000, 20000, 200000, 2000000, 4740332, 20000000, 27204302, 47403320, 200000000, 272043020, 474033200, 2000000000, 2702734302, 2720430200, 4477474032, 4740332000, 20000000000, 27027343020, 27204302000, 44774740320, 47227474032, 47403320000, 200000000000, 270273430200, 272043020000, 447747403200
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

Generated with DrScheme.
Once any term appears that is not a multiple of 10, every multiple of that term by a power of 10 is also a term, i.e., new terms can be generated by appending any number of zeros to previous terms.  Harvey P. Dale, May 02 2021


LINKS



EXAMPLE

47333227304302^2 = 2240434407040720377707707204.


MATHEMATICA

With[{c={0, 2, 3, 4, 7}}, Select[FromDigits/@Tuples[c, 12], SubsetQ[ c, IntegerDigits[ #^2]]&]] (* Harvey P. Dale, May 02 2021 *)


CROSSREFS



KEYWORD

base,nonn


AUTHOR

Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008


STATUS

approved



