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URL: https://oeis.org/A137040

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A137040
Numbers k such that k and k^2 use only the digits 1, 3, 6 and 8.
0
1, 6, 8131, 116881, 1366881
OFFSET
1,2
COMMENTS
Generated with DrScheme.
Likely finite. a(6) > 10^30 if it exists. - Max Alekseyev, Jan 15 2025
LINKS
EXAMPLE
1366881^2 = 1868363668161.
MATHEMATICA
With[{c={1, 3, 6, 8}}, Select[Flatten[Table[FromDigits/@Tuples[c, n], {n, 7}]], SubsetQ[c, IntegerDigits[#^2]]&]] (* Harvey P. Dale, Jul 07 2025 *)
CROSSREFS
Sequence in context: A188979 A158880 A341874 * A357805 A172733 A361901
KEYWORD
base,nonn,more
AUTHOR
Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008
STATUS
approved