A137108 Numbers k such that k and k^2 use only the digits 2, 4, 7 and 9.

2, 7, 27, 49777, 4994777, 49994777, 499979277

Offset

1,1

Comments

Generated with DrScheme.

Links

Table of n, a(n) for n=1..7.

Jonathan Wellons, Tables of Shared Digits [archived]

Example

499979277^2 = 249979277429442729.

Mathematica

okQ[n_]:=Module[{id=Union[IntegerDigits[n^2]]}, And@@Table[MemberQ[ {2, 4, 7, 9}, id[[i]]], {i, Length[id]}]]; Flatten[Table[Select[ FromDigits/@ Tuples[{2, 4, 7, 9}, d], okQ], {d, 10}]] (* Harvey P. Dale, Jun 26 2012 *)

Crossrefs

Sequence in context: A293031 A255487 A077622 * A294128 A099815 A123363

Adjacent sequences: A137105 A137106 A137107 * A137109 A137110 A137111

Keyword

base,nonn,more

Author

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

Status

approved