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A137078 Numbers n such that n and the square of n use only the digits 2, 3, 4 and 9. 0
2, 3, 4943, 499423, 49993443, 4999932923, 499999999293429243923, 499999999999293429243923 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Generated with DrScheme

LINKS

Table of n, a(n) for n=1..8.

J. Wellons, Tables of Shared Digits [BROKEN LINK]

EXAMPLE

4999932923^2 = 24999329234499323929

MAPLE

g:= n -> convert(convert(n, base, 10), set) subset {2, 3, 4, 9}:

Res:= 2, 3:

extend:= proc(n, d) local B; global Res;

B:= {seq(x*10^d+n, x=[2, 3, 4, 9])};

Res:= Res, op(select(t -> g(t^2), B));

op(select(t -> g(t^2 mod 10^(d+1)), B))

end proc:

Agenda:= {2, 3, 4, 9}:

for d from 1 to 25 do Agenda:= map(extend, Agenda, d) od:

sort([Res]); # Robert Israel, Oct 29 2018

CROSSREFS

Cf. A136809.

Sequence in context: A271631 A068826 A085944 * A146026 A115640 A212494

Adjacent sequences:  A137075 A137076 A137077 * A137079 A137080 A137081

KEYWORD

base,nonn

AUTHOR

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

EXTENSIONS

a(7)-a(8) from Andrew Howroyd, Oct 24 2018

STATUS

approved

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Last modified February 17 18:46 EST 2019. Contains 320222 sequences. (Running on oeis4.)