cp's OEIS Frontend

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.

%I A355761 #13 Sep 01 2022 18:56:30
%S A355761 0,3,5,8,9,17,16,17,19,25,35,27,26,37,39,49,41,46,47,53,62,51,66,63,
%T A355761 57,76,77,85,75,77,87,79,93,92,100,112,93,106,97,122,125,107,115,115,
%U A355761 131,138,123,130,126,134,147,164,163,149,151,148,171,159,172,160,172,180,176
%N 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.
%H A355761 Karl-Heinz Hofmann, <a href="/A355761/a355761.pdf">Examples of a(1..8)</a>
%H A355761 Wikipedia, <a href="https://en.wikipedia.org/wiki/Archimedean_spiral">Archimedean spiral</a>
%F A355761 a(n) = A000328(n) - A355760(n).
%e A355761 See the PDF in links.
%Y A355761 Cf. A000328, A355760.
%K A355761 nonn
%O A355761 0,2
%A A355761 _Karl-Heinz Hofmann_, Jul 29 2022