OFFSET
0,3
LINKS
David Dewan, Table of n, a(n) for n = 0..10000
David Dewan, Drawings for n=1..12
FORMULA
a(n) = 4 * A001182(n).
Limit_{n->oo} a(n)/(n^2) = Pi.
MATHEMATICA
a[n_] := 4 Sum[Floor[Sqrt[n^2 - k^2]], {k, n - 1}];
Array[a, 45, 0] (* David Dewan, May 27 2024 *)
PROG
(Python)
from math import isqrt
def A119677(n): return sum(isqrt(k*((n<<1)-k)) for k in range(1, n))<<2 # Chai Wah Wu, Jul 18 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Tomas Kyselica (Tomas.Kyselica(AT)gmail.com), Jul 29 2006
EXTENSIONS
More terms from Don Reble, Aug 01 2006
Name clarified by Kirill Zolotuskiy, Apr 15 2023
STATUS
approved