

A108053


Maximum number of diagonals of a regular ngon that meet at a noncenter point.


0



0, 2, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2
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OFFSET

3,2


LINKS

Table of n, a(n) for n=3..107.
B. Poonen and M Rubinstein, The Number of Intersection Points Made by the Diagonals of a Regular Polygon, 1995.
Sequences formed by drawing all diagonals in regular polygon
Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).


FORMULA

Starting at a(5) = 2, sequence is periodic with period 30.


EXAMPLE

In a 30gon, there are noncenter points where 7 diagonals meet, but no more than 7. Hence a(30) = 7.


MATHEMATICA

Join[{0, 2}, LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}, {2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3}, 103]] (* Ray Chandler, Aug 27 2015 *)


CROSSREFS

Sequence in context: A241476 A309727 A195719 * A327969 A328324 A133501
Adjacent sequences: A108050 A108051 A108052 * A108054 A108055 A108056


KEYWORD

easy,nonn


AUTHOR

David W. Wilson, Jun 01 2005


STATUS

approved



