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A243089 Pseudoprimes to base 7 that are not squarefree. 5

%I #18 Nov 25 2019 03:30:18

%S 25,325,1825,4525,4825,10225,12025,16725,20425,30025,35425,58825,

%T 177025,216525,265525,352225,526825,611425,675925,710425,717025,

%U 746425,772525,784225,834025,877825,1125825,1126225,1439425,1491025,1579225,1935025,1973425,2176525

%N Pseudoprimes to base 7 that are not squarefree.

%C Any term is divisible by the square of a base 7 Wieferich prime (A123693).

%C Intersection of A005938 and A013929. - _Michel Marcus_, Aug 21 2014

%H Amiram Eldar, <a href="/A243089/b243089.txt">Table of n, a(n) for n = 1..3095</a> (terms below 10^12)

%o (PARI) forcomposite(n=1, 1e9, if(Mod(7, n)^(n-1)==1, if(!issquarefree(n), print1(n, ", "))))

%Y Cf. A005938, A123693, A158358, A243010, A243090, A244065.

%K nonn

%O 1,1

%A _Felix Fröhlich_, Aug 18 2014

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Last modified March 28 17:42 EDT 2024. Contains 371254 sequences. (Running on oeis4.)