A136865 - OEIS

A136865

Numbers k such that k and k^2 use only the digits 0, 1, 4, 7 and 9.

0, 1, 7, 10, 70, 97, 100, 107, 700, 701, 970, 997, 1000, 1007, 1049, 1070, 1071, 7000, 7001, 7010, 7071, 9700, 9701, 9970, 9997, 10000, 10007, 10070, 10097, 10490, 10700, 10710, 14107, 70000, 70001, 70010, 70100, 70107, 70499, 70710, 97000, 97001, 97010, 99700, 99970, 99997, 100000, 100007, 100070, 100097, 100499, 100700, 100970, 104900, 107000

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

OFFSET

1,3

COMMENTS

Generated with DrScheme.

LINKS

Jonathan Wellons, Table of n, a(n) for n = 1..1020

J. Wellons, Tables of Shared Digits [archived]

EXAMPLE

4140170401071^2 = 17141010949904404997947041.

MATHEMATICA

With[{c={0, 1, 4, 7, 9}}, Select[FromDigits/@Tuples[c, 6], SubsetQ[ c, IntegerDigits[ #^2]]&]] (* Harvey P. Dale, Aug 13 2020 *)