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 A225185 #34 Sep 08 2024 17:45:27
%S A225185 7,23,31,43,47,71,73,79,103,127,151,157,167,191,193,199,223,239,241,
%T A225185 263,271,277,283,311,313,331,337,359,367,383,397,409,431,439,457,463,
%U A225185 479,487,503,571,577,599,607,631,647,673,691,719,727,733,739,743,751,811,823,839,863,887,911,919,967,983,991,997
%N A225185 Primes p which do not have a primitive root that divides p+1.
%H A225185 Amiram Eldar, <a href="/A225185/b225185.txt">Table of n, a(n) for n = 1..10000</a>
%H A225185 Arto Lepistö, Francesco Pappalardi and Kalle Saari, <a href="https://doi.org/10.1016/j.tcs.2007.03.029">Transposition Invariant Words</a>, Theoret. Comput. Sci., Vol. 380, No. 3 (2007), pp. 377-387.
%e A225185 The primitive roots modulo 97 are 5, 7, 10, 13, 14, 15, 17, 21, 23, 26, 29, 37, 38, 39, ..., and 7 divides 98, so 97 is not a term of this sequence.
%t A225185 q[n_] := PrimeQ[n] && AllTrue[PrimitiveRootList[n], ! Divisible[n + 1, #] &]; Select[Range[1000], q] (* _Amiram Eldar_, Oct 07 2021 *)
%t A225185 Select[Prime[Range[200]],NoneTrue[(#+1)/PrimitiveRootList[#],IntegerQ]&] (* _Harvey P. Dale_, Sep 08 2024 *)
%o A225185 (PARI) forprime(p=2,1000, i=0;fordiv(p+1,X, if(znorder(Mod(X,p))==eulerphi(p), i=1)); if(i==0,print1(p", "))) \\ _V. Raman_, May 04 2012
%o A225185 (Magma) [p: p in PrimesUpTo(1000) | not exists{r: r in [1..p-1] | IsPrimitive(r,p) and IsZero((p+1) mod r)}]; // _Bruno Berselli_, May 10 2013
%Y A225185 Cf. A060749, A225184 (complement), A001122.
%K A225185 nonn
%O A225185 1,1
%A A225185 _N. J. A. Sloane_, May 04 2013
%E A225185 More terms from _V. Raman_, May 04 2013