A137078 Numbers k such that k and k^2 use only the digits 2, 3, 4 and 9.

2, 3, 4943, 499423, 49993443, 4999932923, 499999999293429243923, 499999999999293429243923

Offset

1,1

Comments

Generated with DrScheme.

Links

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

J. Wellons, Tables of Shared Digits [archived] [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,changed

Author

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

Extensions

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

Status

approved