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A137108 Numbers n such that n and the square of n use only the digits 2, 4, 7 and 9. 0
2, 7, 27, 49777, 4994777, 49994777, 499979277 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Generated with DrScheme

LINKS

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

J. Wellons, Tables of Shared Digits

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

AUTHOR

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

STATUS

approved

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Last modified February 23 00:18 EST 2019. Contains 320411 sequences. (Running on oeis4.)