A364828 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.

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, 42, 40, 66, 30, 114, 32, 62, 52, 54, 56, 140, 38, 60, 60, 128, 42, 144, 44, 94, 102, 72, 48, 196, 57, 104, 76, 108, 54, 152, 80, 162, 84, 90, 60, 360, 62, 96, 132, 126

Offset

1,2

Comments

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

Links

Table of n, a(n) for n=1..64.

Matt Henderson, X post, 2023.

Paolo Xausa, Illustration of first terms.

Paolo Xausa, Illustration of a(60).

Formula

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

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

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

Crossrefs

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

Sequence in context: A309796 A359671 A222733 * A141677 A087459 A285103

Adjacent sequences: A364825 A364826 A364827 * A364829 A364830 A364831

Keyword

nonn

Author

Paolo Xausa, Aug 09 2023

Status

approved