A033921 Largest proper substring of 2^n that is a power of 2 (0 if none).

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

Robert Israel, Table of n, a(n) for n = 0..10000

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

Adjacent sequences: A033918 A033919 A033920 * A033922 A033923 A033924

Keyword

nonn,base

Author

N. J. A. Sloane

Extensions

More terms from Patrick De Geest, Jun 15 1998

Status

approved