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A137079 Numbers k such that k and k^2 use only the digits 2, 3, 5 and 6. 1
5, 6, 25, 235, 256, 23566, 2352365325, 23523653335 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Generated with DrScheme.
No more terms < 10^26. - Robert Israel, Nov 24 2023
LINKS
EXAMPLE
2352365325^2 = 5533622622262355625.
MAPLE
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:
sort([R]); # Robert Israel, Nov 24 2023
MATHEMATICA
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 *)
PROG
(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'}]
# Chai Wah Wu, Apr 29 2015
CROSSREFS
Sequence in context: A003226 A088834 A137081 * A163658 A121180 A022165
KEYWORD
base,nonn
AUTHOR
Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008
STATUS
approved

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Last modified March 19 06:29 EDT 2024. Contains 370953 sequences. (Running on oeis4.)