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A364838 a(n) is the number of line intersections (including vertices) inside a regular n-gon after inscribing (always starting from the same point), for each proper divisor d_i of n greater than 1, a regular d_i-gon.

%I A364838 #15 Aug 12 2023 00:42:18
%S A364838 1,2,3,4,5,7,7,8,9,11,11,21,13,15,19,16,17,26,19,31,25,23,23,53,25,27,
%T A364838 27,39,29,73,31,32,37,35,43,86,37,39,43,79,41,91,43,55,69,47,47,121,
%U A364838 49,62,55,63,53,87,63,99,61,59,59,253,61,63,91,64,73,123,67
%N A364838 a(n) is the number of line intersections (including vertices) inside a regular n-gon after inscribing (always starting from the same point), for each proper divisor d_i of n greater than 1, a regular d_i-gon.
%C A364838 Inspired by an X (or Twitter) post by Matt Henderson (see links section).
%H A364838 Matt Henderson, <a href="https://twitter.com/matthen2/status/1639925895254224898">X post</a>, 2023.
%H A364838 Paolo Xausa, <a href="/A364838/a364838.pdf">Illustration of first terms</a>.
%H A364838 Paolo Xausa, <a href="/A364838/a364838_1.pdf">Illustration of a(60)</a>.
%F A364838 a(n) = n if n is prime, a power of 2 or A032741(n) <= 2.
%F A364838 a(n) = A364830(n) + n.
%Y A364838 Cf. A006561, A007569, A032741, A364828, A364829, A364830.
%K A364838 nonn
%O A364838 1,2
%A A364838 _Paolo Xausa_, Aug 09 2023