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 A042998 #17 Jun 26 2022 23:16:33
%S A042998 2,3,5,11,13,17,19,29,37,41,43,53,59,61,67,73,83,89,97,101,107,109,
%T A042998 113,131,137,139,149,157,163,173,179,181,193,197,211,227,229,233,241,
%U A042998 251,257,269,277,281,283,293,307
%N A042998 Primes congruent to {1, 2, 3, 5} (mod 8).
%C A042998 Primes of the form x^2 + y^2 + z^2.
%H A042998 Ray Chandler, <a href="/A042998/b042998.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Vincenzo Librandi)
%H A042998 Wikipedia, <a href="https://en.wikipedia.org/wiki/Legendre%27s_three-square_theorem">Legendre's three-square theorem</a>
%t A042998 Select[Prime[Range[300]],MemberQ[{1,2,3,5},Mod[#,8]]&] (* _Vincenzo Librandi_, Aug 08 2012 *)
%o A042998 (Magma) [p: p in PrimesUpTo(500) | p mod 8 in [1, 2, 3, 5]]; // _Vincenzo Librandi_, Aug 08 2012
%o A042998 (PARI) is(n)=n%8<6 && isprime(n) \\ _Charles R Greathouse IV_, Sep 15 2015
%Y A042998 Cf. A000040, A045403.
%K A042998 nonn,easy
%O A042998 1,1
%A A042998 _N. J. A. Sloane_