A136993 - OEIS

A136993

Numbers k such that k and k^2 use only the digits 1, 2, 4, 6 and 7.

1, 2, 4, 11, 12, 21, 26, 42, 46, 121, 162, 276, 421, 474, 642, 1474, 1621, 1662, 2162, 2174, 4174, 4761, 4762, 4771, 6424, 6642, 11142, 16662, 21621, 24724, 26724, 27224, 46121, 47662, 64162, 64224, 66424, 161761, 161776, 166662, 211462, 214762, 266771, 267671, 414261, 421262, 421621, 462776, 471462, 471642, 477224, 641424, 641671, 664162, 664261

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OFFSET

1,2

COMMENTS

Generated with DrScheme.

LINKS

Jonathan Wellons, Table of n, a(n) for n = 1..520

J. Wellons, Tables of Shared Digits [archived]

EXAMPLE

641612614142421^2 = 411666746626671216217271741241.

MATHEMATICA

Module[{c={1, 2, 4, 6, 7}}, Select[Flatten[Table[FromDigits/@Tuples[c, n], {n, 6}]], SubsetQ[c, IntegerDigits[#^2]]&]] (* Harvey P. Dale, Aug 15 2015 *)

CROSSREFS

Sequence in context: A075488 A363702 A136995 * A136992 A089694 A071069

Adjacent sequences: A136990 A136991 A136992 * A136994 A136995 A136996

KEYWORD

base,nonn

AUTHOR

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

STATUS

approved