A175394 Least nontrivial exponent e > 2 such that n^2 is a substring of n^e (n >= 0).

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

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