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A136955
Numbers k such that k and k^2 use only the digits 0, 4, 6, 7 and 9.
1
0, 7, 64, 70, 97, 640, 700, 970, 997, 6400, 6907, 7000, 7064, 9700, 9970, 9997, 64000, 69070, 70000, 70640, 77974, 97000, 99700, 99747, 99970, 99997, 640000, 666907, 667907, 690700, 700000, 700497, 706400, 774647, 777676, 779740, 970000, 997000, 997470, 999700, 999747, 999970, 999997, 6400000, 6400774, 6669070, 6679070, 6907000, 7000000
OFFSET
1,2
COMMENTS
Generated with DrScheme.
LINKS
J. Wellons, Tables of Shared Digits [archived]
EXAMPLE
700709640764747^2 = 490994000660660790706997974009.
MATHEMATICA
With[{c={0, 4, 6, 7, 9}}, Select[FromDigits/@Tuples[c, 7], SubsetQ[ c, IntegerDigits[ #^2]]&]] (* Harvey P. Dale, Oct 11 2020 *)
CROSSREFS
Sequence in context: A036287 A116231 A195630 * A027767 A055537 A333991
KEYWORD
base,nonn
AUTHOR
Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008
STATUS
approved