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 A038884 #23 Jun 10 2025 19:54:50 %S A038884 2,5,7,11,19,31,37,41,47,59,67,71,73,83,89,97,109,137,149,151,163,167, %T A038884 193,197,223,227,229,239,241,271,281,293,307,317,331,349,353,359,379, %U A038884 383,397,401,409,421,431,449,457 %N A038884 Primes p such that 13 is not a square mod p. %C A038884 Inert rational primes in the field Q(sqrt(13)). - _N. J. A. Sloane_, Dec 26 2017 %C A038884 Primes that are 5, 7, 11, 15, 19, 21 mod 26. - _Charles R Greathouse IV_, Mar 18 2018 %H A038884 Vincenzo Librandi, <a href="/A038884/b038884.txt">Table of n, a(n) for n = 1..1000</a> %H A038884 <a href="/index/Pri#primes_decomp_of">Index to sequences related to decomposition of primes in quadratic fields</a> %F A038884 a(n) ~ 2n log n. - _Charles R Greathouse IV_, Mar 18 2018 %t A038884 Select[Prime@Range[120], JacobiSymbol[13, #] == -1 &] (* _Vincenzo Librandi_, Sep 08 2012 *) %o A038884 (PARI) list(lim)=my(v=List()); forprime(p=2,lim, if(kronecker(13,p)<0, listput(v,p))); Vec(v) \\ _Charles R Greathouse IV_, Mar 18 2018 %K A038884 nonn,easy %O A038884 1,1 %A A038884 _N. J. A. Sloane_ %E A038884 Offset changed from 0 to 1 by _Vincenzo Librandi_, Sep 08 2012