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A175394 Least nontrivial exponent e > 2 such that n^2 is a substring of n^e (n >= 0). 1
3, 3, 6, 6, 7, 3, 7, 6, 22, 11, 3, 13, 26, 54, 123, 27, 27, 40, 100, 43, 6, 43, 54, 42, 12, 3, 37, 43, 9, 37, 6, 19, 102, 102, 43, 96, 83, 45, 67, 34, 12, 128, 168, 102, 182, 44, 152, 104, 184, 52, 3, 17, 35, 75, 164, 67, 127, 22, 134, 98, 7, 124, 117, 146, 77, 146, 156, 87 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Robert Israel, Table of n, a(n) for n = 0..2000

EXAMPLE

a(2)=6 because 2^2=4 is a substring of 2^6=64

a(4)=7 because 4^2=16 is a substring of 4^7=16384.

MAPLE

f:= proc(n) local pat, e;

  pat:= sprintf("%d", n^2);

  for e from 3 do if StringTools:-Search(pat, sprintf("%d", n^e))<> 0 then return e fi od:

end proc:

map(f, [$0..100]); # Robert Israel, Mar 20 2018

MATHEMATICA

lne[n_]:=Module[{e=3, idn2=IntegerDigits[n^2]}, While[!MemberQ[ Partition[ IntegerDigits[n^e], Length[ idn2], 1], idn2], e++]; e]; Array[lne, 70, 0] (* Harvey P. Dale, Aug 17 2013 *)

CROSSREFS

Cf. A008856, A033819, A045537, A074250.

Sequence in context: A105676 A127739 A327142 * A070318 A257537 A219883

Adjacent sequences:  A175391 A175392 A175393 * A175395 A175396 A175397

KEYWORD

base,nonn

AUTHOR

Zak Seidov, Apr 29 2010

STATUS

approved

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Last modified August 12 23:19 EDT 2020. Contains 336440 sequences. (Running on oeis4.)