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 A063950 #8 May 15 2012 06:49:58
%S A063950 0,1,3,4,5,7,9,12,13,15,17,20,21,25,28,33,36,41,45,49,52,57,60,65,68,
%T A063950 73,81,84,89,97,100,105,129,132,145,153,164,169,177,180,185,196,201,
%U A063950 209,217,225,228,257,260,273,292,297,305,313,324,329,345,353,356,385,388,420,425,433,441,481,513,516,561,580,585,609,612,676,689,697,708,713,740,804,817,825,836,868,900,945,1028,1092,1188,1220,1252,1316,1380,1412,1540,1700,1732,1764,1924,2052,2244,2340,2436,2756,2788,2852,3268,3300,3780
%N A063950 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 positive square < n.
%D A063950 J. H. Conway, personal communication, Aug 27, 2001.
%t A063950 r[n_, x_] := Reduce[n == x^2 + y^2 + z^2 + t^2, {y, z, t}, Integers]; solQ[n_, x_] := r[n, x] =!= False; ok[0] = True; ok[n_] := And @@ (solQ[n, #] & ) /@ Range[1, Sqrt[n - 1]]; A063950 = Select[ Select[ Range[0, 4000], Mod[#, 4] != 2 &], If[ok[#], Print[#]; True, False] &](* _Jean-François Alcover_, May 15 2012 *)
%Y A063950 Cf. A063949-A063954.
%K A063950 nonn,easy,nice,fini,full
%O A063950 1,3
%A A063950 _N. J. A. Sloane_, Sep 04 2001
%E A063950 385 added by _T. D. Noe_, Apr 05 2007