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 A216277 #30 Jan 12 2017 02:35:22
%S A216277 2,3,7,11,13,17,19,23,31,37,43,47,53,59,67,71,73,79,83,97,103,107,113,
%T A216277 127,131,137,139,151,157,163,167,173,179,191,193,197,199,211,223,227,
%U A216277 233,239,251,257,263,271,277,283,293,307,311,313,317,331,337,347,353,359,367,373,379,383,397,419
%N A216277 Primes which cannot be written as x^2 + 5*y^2, where x >= 0, y >= 0.
%C A216277 Primes which are not congruent to 1, 5, or 9 (mod 20).
%C A216277 A216286 is the union of {5} and this sequence. - _N. J. A. Sloane_, Sep 04 2012
%D A216277 David A. Cox, Primes of the Form x^2 + n y^2, Wiley, 1989. See Eq. (1.20), p. 19 and Eq. (2.22), p. 32. - _N. J. A. Sloane_, Sep 03 2012
%F A216277 a(n) ~ 4/3 * n log n. - _Charles R Greathouse IV_, Jan 12 2017
%o A216277 (PARI) list(lim)=my(v=List(),t); forprime(p=2,lim, t=p%20; if(t!=1 && t!=9 && t!=5, listput(v,p))); Vec(v) \\ _Charles R Greathouse IV_, Jan 12 2017
%Y A216277 Cf. A033205.
%K A216277 nonn,easy
%O A216277 1,1
%A A216277 _V. Raman_, Sep 03 2012