A136955 - OEIS

A136955

Numbers k such that k and k^2 use only the digits 0, 4, 6, 7 and 9.

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

(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..714

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 *)