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 A175341 Number of coprime pairs (x,y) with x^2+y^2 <= n^2. 3
 0, 4, 8, 16, 32, 48, 72, 88, 120, 152, 192, 224, 264, 312, 384, 440, 480, 544, 616, 672, 768, 832, 928, 1000, 1112, 1192, 1280, 1384, 1488, 1584, 1704, 1816, 1960, 2072, 2224, 2344, 2480, 2600, 2752, 2912, 3064, 3184, 3360, 3480, 3696, 3856, 4016, 4176 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 Wikipedia, Gauss circle problem J. Wu, On the primitive circle problem, Monatsh. Math. 135 (2002), 69. W. G. Zhai, X.D. Cao, On the number of coprime integer pairs within a circle, Acta Arith. 90 (1999), 1. FORMULA a(n) = 4*A176562(n). [From R. J. Mathar, May 07 2010] a(n) = A304651(n^2). - Seiichi Manyama, May 26 2018 EXAMPLE a(2) = 8 counts (x,y) = (-1,-1), (-1,0), (-1,1), (0,-1), (0,1), (1,-1), (1,0) and (1,1). CROSSREFS Cf. A000328, A176562, A304651. Sequence in context: A101434 A293780 A048168 * A317705 A318692 A291441 Adjacent sequences:  A175338 A175339 A175340 * A175342 A175343 A175344 KEYWORD nonn AUTHOR R. J. Mathar, Apr 16 2010 STATUS approved

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Last modified October 20 20:24 EDT 2019. Contains 328273 sequences. (Running on oeis4.)