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 A224779 #4 May 09 2013 22:44:36 %S A224779 2,5,6,9,10,11,13,14,15,17,18,19,21,22,23,25,26,27,29,30,31,33,34,35, %T A224779 37,38,39,41,42,43,45,46,47,49,50,51,53,54,55,57,58,59,61,62,63,65,66, %U A224779 67,69,70,71,73,74,75,77,78,79,81,82,83,85,86,87,89,90,91,93,94,95,97,98,99 %N A224779 One half of the even numbers that are a primitive sum of four nonzero squares at least once. %C A224779 These are the even numbers of A222949 divided by 2. %C A224779 Compare with A224778 where also imprimitive sums are included. Numbers from there, not appearing here, are 8, 20, 24, 32, 36, 40, 44, 52, 56, 60, 68, 72, 76, ... %F A224779 a(n) is one half of the n-th even number of the sequence A222949. %e A224779 a(1) = A222949(1)/2 = 2. The primitive representation of 4 is denoted by [1, 1, 1, 1], standing for 1^2 + 1^2 + 1^2 + 1^2. %e A224779 a(8) = A222949(18)/2 =14, with two primitive representations for 28, namely [1, 1, 1, 5] and [1, 3, 3, 3]. There is also the imprimitive representation [2, 2, 2, 4]. %e A224779 8 does not appear because the only representation of 16 comes from [2, 2, 2, 2] which is imprimitive. %Y A224779 Cf. A224778 (imprimitive case). %K A224779 nonn %O A224779 1,1 %A A224779 _Wolfdieter Lang_, May 09 2013