cp's OEIS Frontend

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

%I A175394 #9 Mar 21 2018 04:34:54
%S A175394 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,
%T A175394 37,43,9,37,6,19,102,102,43,96,83,45,67,34,12,128,168,102,182,44,152,
%U A175394 104,184,52,3,17,35,75,164,67,127,22,134,98,7,124,117,146,77,146,156,87
%N A175394 Least nontrivial exponent e > 2 such that n^2 is a substring of n^e (n >= 0).
%H A175394 Robert Israel, <a href="/A175394/b175394.txt">Table of n, a(n) for n = 0..2000</a>
%e A175394 a(2)=6 because 2^2=4 is a substring of 2^6=64
%e A175394 a(4)=7 because 4^2=16 is a substring of 4^7=16384.
%p A175394 f:= proc(n) local pat,e;
%p A175394   pat:= sprintf("%d",n^2);
%p A175394   for e from 3 do if StringTools:-Search(pat, sprintf("%d",n^e))<> 0 then return e fi od:
%p A175394 end proc:
%p A175394 map(f, [$0..100]); # _Robert Israel_, Mar 20 2018
%t A175394 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 *)
%Y A175394 Cf. A008856, A033819, A045537, A074250.
%K A175394 base,nonn
%O A175394 0,1
%A A175394 _Zak Seidov_, Apr 29 2010