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%I #6 Apr 09 2018 02:48:04
%S 0,2,2,20,28,70,110,192,256,402,498,708,884,1166,1422,1800,2104,2594,
%T 3026,3588,4140,4918,5542,6432,7224,8186,9122,10380,11460,12790,14094,
%U 15624,17080,18882,20458,22500,24364,26590,28678,31136,33400
%N Closed 3-dimensional ball numbers (version 2): a(n)= number of integer points (i,j,k) contained in a closed ball of diameter n, centered at (1/2,0,0).
%C a(n)/(n/2)^3->4/3*Pi
%H Robert Israel, <a href="/A053593/b053593.txt">Table of n, a(n) for n = 0..2000</a>
%p N:= 100: # to get a(0)..a(N)
%p B:= Array(0..N^2):
%p B[0]:= 1:
%p for x from 1 to N do
%p for y from 0 to x do
%p r:= x^2 + y^2;
%p if r > N^2 then break fi;
%p if y=0 or y=x then B[r]:= B[r]+4 else B[r]:= B[r]+8 fi
%p od od:
%p BL:= convert(B,list):
%p SL:= ListTools:-PartialSums(BL):
%p f:= n -> add(SL[floor((n^2+3)/4-x^2+x)], x=ceil(1/2-n/2)..n/2+1/2):
%p seq(f(n),n=0..N); # _Robert Israel_, Apr 09 2018
%K easy,nonn
%O 0,2
%A Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Jan 19 2000
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