A137007 Numbers k such that k and k^2 use only the digits 1, 2, 5 and 7.

1, 5, 11, 15, 715

Offset: 1

Author

Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008

Keywords

• base
• nonn
• more

Comments

Generated with DrScheme.

No additional terms up to and including 7,777,777,777. - Harvey P. Dale, Sep 04 2018

No additional terms up to 10^26. - L. Joris Perrenet, Jul 02 2020

No additional terms up to 10^39. - Michael S. Branicky, Apr 12 2024

Examples

			715^2 = 511225.
		

Links

• Jonathan Wellons, Tables of Shared Digits [archived]

Programs

Mathematica

Module[{nn=10,c={1,2,5,7}},Select[Flatten[Table[FromDigits/@Tuples[c,n],{n,nn}]],SubsetQ[c,IntegerDigits[#^2]]&]] (* Harvey P. Dale, Sep 04 2018 *)