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 A214515 #5 Jul 29 2012 15:23:33
%S A214515 16,21,26,31,36,37,42,47,52,58,61,63,66,68,71,76,79,82,84,87,92,100,
%T A214515 103,106,108,111,116,124,127,132,133,138,143,148,151,154,156,159,164,
%U A214515 172,175,178,180,181,183,186,188,191,196,199,202,204,207,212,220,223
%N A214515 Numbers of the form p^2 + q^2 + r^2 + s^2, where p, q, r, and s are primes.
%H A214515 T. D. Noe, <a href="/A214515/b214515.txt">Table of n, a(n) for n = 1..10000</a>
%t A214515 nn = 10^3; ps = Prime[Range[PrimePi[Sqrt[nn]]]]; t = Flatten[Table[ps[[i]]^2 + ps[[j]]^2 + ps[[k]]^2 + ps[[l]]^2, {i, Length[ps]}, {j, i, Length[ps]}, {k, j, Length[ps]}, {l, k, Length[ps]}]]; t = Select[t, # <= nn &]; Union[t]
%Y A214515 Cf. A045636 (two primes), A214514 (three primes).
%K A214515 nonn
%O A214515 1,1
%A A214515 _T. D. Noe_, Jul 29 2012