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A033921
Largest proper substring of 2^n that is a power of 2 (0 if none).
15
0, 0, 0, 0, 1, 2, 4, 8, 2, 2, 4, 8, 4, 8, 16, 32, 0, 2, 4, 8, 8, 2, 4, 8, 16, 32, 64, 8, 8, 8, 8, 64, 4, 8, 8, 8, 8, 8, 8, 8, 16, 32, 8, 8, 16, 32, 64, 32, 8, 4, 8, 8, 4, 4, 8, 8, 4, 8, 8, 64, 8, 8, 16, 8, 16, 32, 64, 64, 8, 8, 16, 32, 64, 32, 8, 16, 32, 64, 4, 8, 8, 16, 32, 64, 16, 32, 64, 8, 8
OFFSET
0,6
LINKS
EXAMPLE
2^15={32}768, so a(15)=32.
MAPLE
for n from 0 to 100 do
L[n]:= sprintf("%d", 2^n);
A[n]:= 0;
for k from n-1 by -1 to 0 do
if StringTools[Search](L[k], L[n]) <> 0 then
A[n]:= 2^k; break
fi
od
od:
seq(A[n], n=0..100); # Robert Israel, Aug 16 2018
CROSSREFS
Cf. A000079.
Sequence in context: A215452 A362985 A175131 * A167420 A195711 A200610
KEYWORD
nonn,base
EXTENSIONS
More terms from Patrick De Geest, Jun 15 1998
STATUS
approved