A137009 Numbers k such that k and k^2 use only the digits 1, 2, 5, 7 and 9.

1, 5, 11, 15, 27, 77, 227, 527, 715, 1515, 1711, 2777, 7227, 7715, 22715, 52915, 71911, 97527, 159911, 275527, 277977, 715511, 727511, 977511, 2791515, 7219777, 7557511, 7715515, 7727711, 7727715, 9591515, 9777515, 9797511, 9797715, 9955511, 11292915, 12292915, 17255515, 27771527, 27797715, 27797977, 27915515, 71971911, 72299211

Offset

1,2

Comments

Generated with DrScheme.

Links

Jonathan Wellons, Table of n, a(n) for n = 1..272

J. Wellons, Tables of Shared Digits [archived]

Example

759722171291527^2 = 577177777551912291775221991729.

Mathematica

With[{c={1, 2, 5, 7, 9}}, Select[Flatten[Table[FromDigits/@Tuples[c, n], {n, 8}]], SubsetQ[ c, IntegerDigits[#^2]]&]] (* Harvey P. Dale, Oct 14 2020 *)

Crossrefs

Sequence in context: A314078 A314079 A372113 * A340131 A290199 A034905

Adjacent sequences: A137006 A137007 A137008 * A137010 A137011 A137012

Keyword

base,nonn

Author

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

Status

approved