This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A205581 #21 Aug 29 2018 03:27:52 %S A205581 4111,7841,10111,15391,15991,16061,20011,21031,22699,32299,32957, %T A205581 35911,43963,45127,45631,47431,49831,51199,53173,53731,58111,59671, %U A205581 60331,64231,71761,74311,76039,78079,81331,81761,83311,83431,87541,98911,100621,102871,104729 %N A205581 Primes p whose smallest positive primitive root (mod p) is not squarefree. %C A205581 A061325 is a proper subsequence. %C A205581 A061330 is also a proper subsequence. - _Michel Marcus_, Feb 09 2016 %C A205581 Most of the terms have least primitive root 12. - _Jianing Song_, Aug 29 2018 %H A205581 Jianing Song, <a href="/A205581/b205581.txt">Table of n, a(n) for n = 1..1265</a> %H A205581 Stephen D. Cohen, Tim Trudgian, <a href="http://arxiv.org/abs/1602.02440">On the least square-free primitive root modulo p</a>, arXiv:1602.02440 [math.NT], 2016. %e A205581 4111 is in the sequence since it is prime and its smallest primitive root (mod 4111) is 12. %e A205581 53173 is in the sequence since it is prime and its smallest primitive root (mod 53173) is 18. %t A205581 Select[Prime[Range[10000]],!SquareFreeQ[PrimitiveRoot[#]]&] (* version 7.0 *) %o A205581 (PARI) lista(nn) = forprime(p=2, nn, if (! issquarefree(lift(znprimroot(p))), print1(p, ", "))); %Y A205581 Cf. A061325, A061330. %K A205581 nonn %O A205581 1,1 %A A205581 _Emmanuel Vantieghem_, Jan 29 2012