If a circle is centered on the origin and has radius r, it may pass through some points with integer coordinates. In fact, by symmetry, this will be a multiple of 4.
Find the smallest radius that will pass through 4n integer points where n=1,2,3,4,5.
Feel free to go further.
(In reply to OEIS sequence
by Brian Smith)
The correct sequence is NOT the one you quote:
Please compare a(5) and on.
Edited on March 1, 2011, 4:52 pm