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A304651 Number of coprime pairs (x,y) with x^2 + y^2 <= n. 3
0, 4, 8, 8, 8, 16, 16, 16, 16, 16, 24, 24, 24, 32, 32, 32, 32, 40, 40, 40, 40, 40, 40, 40, 40, 48, 56, 56, 56, 64, 64, 64, 64, 64, 72, 72, 72, 80, 80, 80, 80, 88, 88, 88, 88, 88, 88, 88, 88, 88, 96, 96, 96, 104, 104, 104, 104, 104, 112, 112, 112, 120, 120, 120, 120 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..10000

FORMULA

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

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. A000089, A175341, A305117.

Sequence in context: A040012 A054006 A029679 * A187768 A141284 A272812

Adjacent sequences:  A304648 A304649 A304650 * A304652 A304653 A304654

KEYWORD

nonn

AUTHOR

Seiichi Manyama, May 26 2018

STATUS

approved

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Last modified September 21 11:18 EDT 2019. Contains 327253 sequences. (Running on oeis4.)