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 A063953 #9 Dec 10 2013 16:09:39
%S A063953 0,1,3,4,5,9,12,13,17,20,21,25,33,36,41,45,49,52,57,65,68,73,81,84,89,
%T A063953 97,100,105,129,132,145,153,164,169,177,180,185,196,201,209,217,225,
%U A063953 228,257,260,273,292,297,305,313,324,329,345,353,356,385,388,420,425,433,441,481,513,516,561,580,585,609,612,676,689,697,708,713,740,804,817,825,836,868,900,945,1028,1092,1188,1220,1252,1316,1380,1412,1540,1700,1732,1764,1924,2052,2244,2340,2436,2756,2788,2852,3268,3300,3780
%N A063953 Of course every number is the sum of 4 squares; these are the numbers not of the form 4m+2 such that the first square can be taken to be any square < n.
%D A063953 J. H. Conway, personal communication, Aug 27, 2001.
%t A063953 ok[n_] := And @@ (Reduce[# + x^2 + y^2 + z^2 == n, {x, y, z}, Integers] =!= False & /@ Select[ Range[n-1], IntegerQ[Sqrt[#]]& ]); Reap[ Do[ If[Mod[n, 4] != 2 && ok[n], Print[n]; Sow[n]], {n, 0, 4000}]][[2, 1]] (* _Jean-François Alcover_, Jun 22 2012 *)
%Y A063953 Cf. A063949-A063954.
%K A063953 nonn,easy,nice,fini,full
%O A063953 0,3
%A A063953 _N. J. A. Sloane_, Sep 04 2001