%I #4 Mar 30 2012 17:22:26
%S 0,20,60,128,228,380,440,684,860,1068,1328,1548,1940,2288,2484,2924,
%T 3300,3824,4140,4700,5240,5484,6260,6864,7340,8180,8676,9392,9804,
%U 10988,11208,12572,13100,13860,14792,15588,16604,17328,18500,19292
%N Number of solutions to n^2 < x^2 + y^2 + z^2 < (n+1)^2; number of lattice points between spheres of radii n and n+1.
%F a(n) = A078183(n+1) - A000605(n)
%t Table[Sum[SquaresR[3, k], {k, n^2 + 1, (n + 1)^2 - 1}], {n, 0, 50}]
%Y Cf. A000605, A078183.
%K nonn
%O 0,2
%A _T. D. Noe_, Nov 21 2002