A364828 - OEIS

%I #16 Aug 12 2023 00:40:13

%S 1,2,4,6,6,12,8,14,13,18,12,36,14,24,28,30,18,46,20,52,36,36,24,88,31,

%T 42,40,66,30,114,32,62,52,54,56,140,38,60,60,128,42,144,44,94,102,72,

%U 48,196,57,104,76,108,54,152,80,162,84,90,60,360,62,96,132,126

%N a(n) is the number of regions inside a circle after inscribing (always starting from the same point), for each divisor d_i of n greater than 1, a regular d_i-gon.

%C Inspired by an X (or Twitter) post by Matt Henderson (see links section).

%H Matt Henderson, <a href="https://twitter.com/matthen2/status/1639925895254224898">X post</a>, 2023.

%H Paolo Xausa, <a href="/A364828/a364828.pdf">Illustration of first terms</a>.

%H Paolo Xausa, <a href="/A364828/a364828_1.pdf">Illustration of a(60)</a>.

%F a(n) = n + 1, if n is prime.

%F a(n) = 2*(n-1), if n > 1 is a power of 2.

%F a(n) = A364829(n) + n.

%Y Cf. A006600, A006533, A364829, A364830, A364838.

%K nonn

%O 1,2

%A _Paolo Xausa_, Aug 09 2023