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 A304651 Number of coprime pairs (x,y) with x^2 + y^2 <= n. 3

%I

%S 0,4,8,8,8,16,16,16,16,16,24,24,24,32,32,32,32,40,40,40,40,40,40,40,

%T 40,48,56,56,56,64,64,64,64,64,72,72,72,80,80,80,80,88,88,88,88,88,88,

%U 88,88,88,96,96,96,104,104,104,104,104,112,112,112,120,120,120,120

%N Number of coprime pairs (x,y) with x^2 + y^2 <= n.

%H Seiichi Manyama, <a href="/A304651/b304651.txt">Table of n, a(n) for n = 0..10000</a>

%F a(n) = a(n-1) + 4*A000089(n) for n > 0.

%e a(2) = 8 counts (x,y) = (-1,-1), (-1,0), (-1,1), (0,-1), (0,1), (1,-1), (1,0) and (1,1).

%Y Cf. A000089, A175341, A305117.

%K nonn

%O 0,2

%A _Seiichi Manyama_, May 26 2018

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Last modified October 22 16:15 EDT 2019. Contains 328318 sequences. (Running on oeis4.)