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%I #32 Aug 03 2023 01:42:53
%S 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,
%T 27,28,29,31,32,33,34,35,36,37,38,40,41,42,43,44,45,47,48,49,52,53,55,
%U 56,58,59,60,61,64,67,68
%N Numbers that are not the sum of 4 distinct nonzero squares.
%C It has been shown that 157 is the last odd number in this sequence. Beyond 157, the terms grow exponentially. - _T. D. Noe_, Apr 07 2007
%C Taking a(86) to a(120) as initial terms, A004441(n) satisfies the 35th-order recurrence relation u(n) = 4*u(n-35). - _Ant King_, Aug 13 2010
%H T. D. Noe, <a href="/A004441/b004441.txt">Table of n, a(n) for n = 1..1000</a> (using A004195 and A004196)
%H Paul T. Bateman, Adolf J. Hildebrand and George B. Purdy, <a href="http://matwbn.icm.edu.pl/ksiazki/aa/aa67/aa6745.pdf">Sums of distinct squares</a>, Acta Arith. 67 (1994), 349-380.
%H H. D. Nguyen and D. Taggart, <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.391.2522&rep=rep1&type=pdf">Mining the OEIS: Ten Experimental Conjectures</a>, 2013. Mentions this sequence. - From _N. J. A. Sloane_, Mar 16 2014
%H <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>
%t data1=Reduce[w^2+x^2+y^2+z^2==# && 0<w<x<y<z<#,{w,x,y,z},Integers]&/@Range[1000];data2=If[Head[ # ]===And,1,Length[ # ]] &/@data1;DeleteCases[Table[If[data2[[k]]>0,0,k],{k,1,Length[data2]}],0] (* _Ant King_, Aug 13 2010 *)
%Y Cf. A004195, A004196, A004433 (complement).
%K nonn
%O 1,2
%A _N. J. A. Sloane_
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