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 A070270 #10 Oct 07 2021 02:01:21 %S A070270 41,109,151,229,251,271,313,337,367,733,761,971,991,1021,1031,1069, %T A070270 1289,1297,1303,1429,1471,1489,1759,1783,1789,1811,1871,1873,1879, %U A070270 2137,2411,2441,2551,2749,2791,2971,3001,3061,3079,3109,3221,3229,3251,3301 %N A070270 Primes for which the smallest positive primitive root is even and nonprime. %H A070270 Amiram Eldar, <a href="/A070270/b070270.txt">Table of n, a(n) for n = 1..10000</a> %t A070270 Select[Prime[Range[500]],EvenQ[PrimitiveRoot[#]]&&PrimitiveRoot[#]!=2&] (* _Harvey P. Dale_, Jul 31 2015 *) %o A070270 (PARI) forprime(n=1,5000,if((-1)^(lift(znprimroot(n))*(1-isprime(lift(znprimroot(n)))))==1+isprime(lift(znprimroot(n))),print1(n,","))) %Y A070270 Cf. A047936, A001918. %K A070270 easy,nonn %O A070270 1,1 %A A070270 _Benoit Cloitre_, May 09 2002