A137018 Numbers k such that k and k^2 use only the digits 1, 2, 7, 8 and 9.

1, 9, 11, 17, 27, 89, 91, 911, 989, 2777, 2827, 2877, 9911, 27877, 28127, 88189, 88277, 88877, 98989, 99891, 172891, 279127, 282827, 287891, 988877, 2879189, 9989891, 9998891, 29711811, 87919777, 88978189, 99899891, 112818127, 277817777, 277871911, 277987917, 278781777, 279781911, 287919777, 888812811, 1727112877, 2778718989

Offset

1,2

Comments

Generated with DrScheme.

Links

Jonathan Wellons, Table of n, a(n) for n = 1..158

J. Wellons, Tables of Shared Digits [archived]

Example

278787181898989^2 = 77722292791179979928199222121.

Mathematica

With[{d={1, 2, 7, 8, 9}}, Table[Select[FromDigits/@Tuples[d, n], SubsetQ[d, IntegerDigits[#^2]]&], {n, 10}]]//Flatten (* Harvey P. Dale, Aug 09 2025 *)

Crossrefs

Sequence in context: A111391 A077788 A339048 * A182391 A346465 A263722

Adjacent sequences: A137015 A137016 A137017 * A137019 A137020 A137021

Keyword

base,nonn

Author

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

Status

approved