A218711 - OEIS

%I #6 Nov 05 2012 14:59:19

%S 0,1,8,23,51,90,157,230,341,471,639,835,1063,1340,1671,2022,2443,2893,

%T 3428,4004,4653,5359,6133,6977,7907,8886,9991,11152,12428,13724,15192,

%U 16683,18358,20072,21932,23880,25941,28117,30397,32822,35376,38013,40840,43765,46880,50090,53448,56911,60583,64379

%N Number of nonnegative solutions to x^2 + y^2 + z^2 < n^2.

%F a(n) = A000604(n) - A181788(n).

%o (JavaScript)

%o for (i=0;i<50;i++) {

%o d=0;

%o for (a=0;a<=i;a++)

%o for (b=0;b<=i;b++)

%o for (c=0;c<=i;c++)

%o if (Math.pow(a,2)+Math.pow(b,2)+Math.pow(c,2)<Math.pow(i,2)) d++;

%o document.write(d+", ");

%o }

%Y Cf. A000604, A181788.

%K nonn

%O 0,3

%A _Jon Perry_, Nov 04 2012