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 A071339 a(n) = the maximum number of lattice points touched by an origin-centered circle with radius <= n. 9
 1, 4, 4, 8, 8, 12, 12, 12, 12, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 36, 36, 36 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Hugo Pfoertner, FORTRAN program for A071339-A071347 FORMULA a(n) = max(i=0 to n^2) A004018(i) EXAMPLE a(5 to 8)=12 because the circle with radius 5 touches 12 lattice points: (+-1,+-2), (+-2,+-1), (+-5,0), (0,+-5); but no circle touches more, until the radius is sqrt(65). CROSSREFS Cf. A004018, A071339-A071347, A071383-A071385. Sequence in context: A196054 A292135 A053249 * A146890 A168273 A278933 Adjacent sequences:  A071336 A071337 A071338 * A071340 A071341 A071342 KEYWORD easy,nonn AUTHOR Hugo Pfoertner, May 22 2002 EXTENSIONS Edited by Don Reble, Nov 06 2005 STATUS approved

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Last modified April 14 01:17 EDT 2021. Contains 342941 sequences. (Running on oeis4.)