A359861 Number of edges among all distinct circles that can be constructed from a 2 X n square grid of points using only a compass.

4, 84, 420, 1604, 3904, 8444, 15524, 27356, 43540, 67720, 99088, 142912, 196820, 267580, 352844, 460432, 586592, 741852, 920528, 1136888, 1382360, 1672384, 1998964, 2380940, 2804292, 3291376, 3830048, 4444176, 5116128, 5876580, 6703220, 7631352, 8634796, 9751064, 10956320

Offset: 1

Author

Scott R. Shannon, Jan 16 2023

Keywords

• nonn

Comments

See A359859 and A359860 for further details and images of the circles. No formula for a(n) is known.

Examples

			a(n) = A359859(n) + A359860(n) - 1 by Euler's formula.
		

Links

• Lucas A. Brown, Python program.

Crossrefs

Cf. A359859 (vertices), A359860 (regions), A359862 (k-gons), A001859, A359254.

Extensions

a(19)-a(35) from Lucas A. Brown, Oct 11 2024