A137117 Numbers k such that k and k^2 use only the digits 2, 5, 7 and 9.

5, 27, 77, 527, 7227, 27797977

Offset

1,1

Comments

Generated with DrScheme.

No further terms up to 10^12. - Harvey P. Dale, Oct 02 2017

No further terms up to 10^38. - Michael S. Branicky, May 27 2021

Links

Table of n, a(n) for n=1..6.

Jonathan Wellons, Tables of Shared Digits [archived].

Example

27797977^2 = 772727525292529.

Mathematica

With[{c={2, 5, 7, 9}}, Table[Select[FromDigits/@Tuples[c, n], SubsetQ[c, IntegerDigits[ #^2]]&], {n, 8}]]//Flatten (* Harvey P. Dale, Oct 02 2017 *)

Prog

(Python) # uses auptod in A137110
print(auptod(16, only="2579")) # Michael S. Branicky, May 27 2021

Crossrefs

Cf. A137110, A137116.

Sequence in context: A048712 A121876 A137116 * A064675 A135713 A085740

Adjacent sequences: A137114 A137115 A137116 * A137118 A137119 A137120

Keyword

base,nonn,more

Author

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

Status

approved