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A136819
Numbers k such that k and k^2 use only the digits 0, 1, 2, 4 and 7.
1
0, 1, 2, 10, 11, 12, 20, 21, 100, 101, 102, 110, 120, 200, 201, 210, 421, 1000, 1001, 1002, 1010, 1011, 1012, 1020, 1021, 1071, 1100, 1101, 1102, 1200, 1201, 2000, 2001, 2010, 2011, 2100, 2101, 4210, 10000, 10001, 10002, 10010, 10011, 10012, 10020, 10021, 10100, 10110, 10120, 10200, 10210, 10710, 11000, 11001, 11002, 11010, 11011, 11020, 12000
OFFSET
1,3
COMMENTS
Generated with DrScheme.
LINKS
EXAMPLE
4702140701^2 = 22110127172000771401.
MATHEMATICA
With[{c={0, 1, 2, 4, 7}}, Select[Union[Flatten[FromDigits/@Tuples[c, 5]]], SubsetQ[ c, IntegerDigits[ #^2]]&]] (* Harvey P. Dale, Mar 24 2018 *)
CROSSREFS
Sequence in context: A136810 A136821 A105116 * A136816 A188264 A169683
KEYWORD
base,nonn
AUTHOR
Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008
STATUS
approved