OFFSET
0,2
COMMENTS
Number of ordered pairs of integers (x,y) with x^2 + y^2 <= n^2 and y >= 0. [Reinhard Zumkeller, Jan 23 2012]
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 0..1000
FORMULA
Partial sums of A036696. - Sean A. Irvine, Nov 22 2020
MATHEMATICA
a[n_] := (k = 0; Do[If[x^2 + y^2 <= n^2, k++], {x, -n, n}, {y, 0, n}]; k); Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Oct 08 2016 *)
PROG
(Haskell)
a036695 n = length [(x, y) | x <- [-n..n], y <- [0..n], x^2 + y^2 <= n^2]
-- Reinhard Zumkeller, Jan 23 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved