Return to Question

Write a program or function that given an integer radius r returns the number of unit squares the circle with radius r centered at the origin passes through. If the circle passes exactly through a point on the grid that does not count as passing through the adjacent unit squares.

Here's an illustration for r = 5:

illustration ^{Illustration by Kival Ngaokrajang, found on OEIS}

Examples:

0 → 0
1 → 4
4 → 28
49 → 388
50 → 380
325 → 2540
5524 → 44180
5525 → 44020

Write a program or function that given an integer radius r returns the number of unit squares the circle with radius r centered at the origin passes through. If the circle passes exactly through a point on the grid that does not count as passing through the adjacent unit squares.

Here's an illustration for r = 5:

illustration ^{Illustration by Kival Ngaokrajang, found on OEIS}

Examples:

0 → 0
1 → 4
4 → 28
5 → 28
49 → 388
50 → 380
325 → 2540
5524 → 44180
5525 → 44020

Write a program or function that given an integer radius r returns the number of unit squares the circle with radius r centered at the origin passes through. If the circle passes exactly through a point on the grid that does not count as passing through the adjacent unit squares.

Here's an illustration for r = 5:

illustration

Examples:

0 → 0
1 → 4
4 → 28
49 → 388
50 → 380
325 → 2540
5524 → 44180
5525 → 44020

Write a program or function that given an integer radius r returns the number of unit squares the circle with radius r centered at the origin passes through. If the circle passes exactly through a point on the grid that does not count as passing through the adjacent unit squares.

Here's an illustration for r = 5:

illustration ^{Illustration by Kival Ngaokrajang, found on OEIS}

Examples:

0 → 0
1 → 4
4 → 28
49 → 388
50 → 380
325 → 2540
5524 → 44180
5525 → 44020