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A136863
Numbers k such that k and k^2 use only the digits 0, 1, 4 and 7.
0
0, 1, 10, 100, 1000, 1071, 10000, 10710, 100000, 107100, 1000000, 1071000, 10000000, 10710000, 100000000, 107100000, 1000000000, 1071000000, 10000000000, 10710000000, 100000000000, 107100000000, 1000000000000, 1071000000000, 10000000000000, 10710000000000, 100000000000000, 107100000000000
OFFSET
1,3
COMMENTS
Generated with DrScheme.
EXAMPLE
107100000000000^2 = 11470410000000000000000000000.
MATHEMATICA
With[{c={0, 1, 4, 7}}, Select[Flatten[FromDigits/@Tuples[c, 15]], SubsetQ[ c, IntegerDigits[ #^2]]&]] (* Harvey P. Dale, Feb 08 2023 *)
CROSSREFS
Sequence in context: A115798 A077439 A136839 * A031201 A228989 A072083
KEYWORD
base,nonn
AUTHOR
Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008
STATUS
approved