A355761 a(n) is the number of grid points in a square lattice strictly outside of the area enclosed by n loops of an Archimedean spiral and inside (or on the boundary) of a circle with radius n.

0, 3, 5, 8, 9, 17, 16, 17, 19, 25, 35, 27, 26, 37, 39, 49, 41, 46, 47, 53, 62, 51, 66, 63, 57, 76, 77, 85, 75, 77, 87, 79, 93, 92, 100, 112, 93, 106, 97, 122, 125, 107, 115, 115, 131, 138, 123, 130, 126, 134, 147, 164, 163, 149, 151, 148, 171, 159, 172, 160, 172, 180, 176

Offset

0,2

Links

Table of n, a(n) for n=0..62.

Karl-Heinz Hofmann, Examples of a(1..8)

Wikipedia, Archimedean spiral

Formula

a(n) = A000328(n) - A355760(n).

Example

See the PDF in links.

Crossrefs

Cf. A000328, A355760.

Sequence in context: A022769 A343114 A349679 * A306948 A067241 A360030

Adjacent sequences: A355758 A355759 A355760 * A355762 A355763 A355764

Keyword

nonn

Author

Karl-Heinz Hofmann, Jul 29 2022

Status

approved