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A137079
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Numbers k such that k and k^2 use only the digits 2, 3, 5 and 6.
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1
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OFFSET
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1,1
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COMMENTS
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Generated with DrScheme.
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LINKS
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EXAMPLE
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2352365325^2 = 5533622622262355625.
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MAPLE
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Good := {2, 3, 5, 6}: R:= 5, 6:
G[1]:= {5, 6}:
for d from 2 to 26 do
G[d]:= select(t -> member(floor((t^2 mod 10^d)/10^(d-1)), Good), map(t -> seq(10^(d-1)*i+t, i=Good), G[d-1]));
for t in G[d] do
if convert(convert(t^2, base, 10), set) subset Good then R:= R, t fi
od od:
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MATHEMATICA
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fQ[n_] := Block[{d = DigitCount@ n}, Total@ Delete[d, {{2}, {3}, {5}, {6}}] == 0]; Select[Range@ 100000, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, Apr 29 2015 *)
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PROG
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(Python)
from itertools import product
A137079_list = [int(''.join(a)+b) for l in range(10) for a in product('2356', repeat = l) for b in ('5', '6') if set(str(int(''.join(a)+b)**2)) <= {'2', '3', '5', '6'}]
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008
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STATUS
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approved
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