A136959 - OEIS

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A136959

Numbers k such that k and k^2 use only the digits 0, 4, 7, 8 and 9.

0, 7, 70, 88, 97, 700, 707, 878, 880, 948, 970, 997, 7000, 7007, 7070, 8780, 8798, 8800, 8947, 9480, 9700, 9898, 9970, 9997, 70000, 70007, 70070, 70700, 70707, 87798, 87800, 87980, 88000, 89448, 89470, 94800, 97000, 98980, 99448, 99700, 99970, 99997, 700000, 700007, 700070, 700700, 707000, 707070, 877898, 877980, 877998, 878000, 879800

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Generated with DrScheme.

LINKS

Jonathan Wellons, Table of n, a(n) for n = 1..1058

J. Wellons, Tables of Shared Digits [archived]

EXAMPLE

8989409879898^2 = 80809489988807774784490404.

MATHEMATICA

With[{c={0, 4, 7, 8, 9}}, Select[FromDigits/@Tuples[c, 6], SubsetQ[ c, IntegerDigits[ #^2]]&]] (* Harvey P. Dale, Jun 02 2019 *)