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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.
1
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
FORMULA
a(n) = A000328(n) - A355760(n).
EXAMPLE
See the PDF in links.
CROSSREFS
Sequence in context: A022769 A343114 A349679 * A306948 A067241 A360030
KEYWORD
nonn
AUTHOR
Karl-Heinz Hofmann, Jul 29 2022
STATUS
approved