OFFSET
0,3
COMMENTS
See A255238 for a Gauss' circle problem comment and a link.
FORMULA
a(n) = sum((-1)^m*T(n, m), m = 0..n), n >= 0, with T(n, m) = A255238(n, m) = 1 + floor(sqrt(n^2 - m^2)).
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Mar 12 2015
STATUS
approved