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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

Table of n, a(n) for n=0..67.

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 February 16 03:15 EST 2019. Contains 320140 sequences. (Running on oeis4.)