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A030477
Numbers k such that k^2 has property that all even digits occur together and all odd digits occur together.
3
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 17, 18, 20, 21, 22, 24, 25, 28, 29, 30, 32, 34, 38, 40, 42, 44, 45, 47, 49, 51, 53, 56, 58, 60, 62, 65, 67, 68, 72, 76, 78, 79, 80, 83, 86, 88, 91, 92, 93, 98, 100, 102, 108, 118, 120, 122, 124, 132, 134, 138, 140
OFFSET
1,3
LINKS
MAPLE
filter:= proc(n) local L, x, m;
L:= convert(n^2, base, 10) mod 2;
if n::odd then
if not member(0, L, m) then return true fi;
convert(L[m..-1], set) = {0}
else
if not member(1, L, m) then return true fi;
convert(L[m..-1], set) = {1}
fi
end proc:
select(filter, [$0..1000]); # Robert Israel, Oct 27 2024
PROG
(Python)
def ok(n):
s = "".join("0" if d in "02468" else "1" for d in str(n**2))
return len(set(s.rstrip(s[-1]))) < 2
print([k for k in range(141) if ok(k)]) # Michael S. Branicky, Oct 27 2024
CROSSREFS
Cf. A030476.
Sequence in context: A055238 A100952 A303332 * A178859 A165412 A180042
KEYWORD
nonn,base,changed
STATUS
approved