

A292105


Irregular triangle read by rows: T(n,k) = the number of interior points that are the intersections of exactly k chords in the configuration A006561(n) (n >= 1, k >= 1).


3



0, 0, 0, 0, 1, 0, 5, 0, 12, 1, 0, 35, 0, 40, 8, 1, 0, 126, 0, 140, 20, 0, 1, 0, 330, 0
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OFFSET

1,7


LINKS

Table of n, a(n) for n=1..26.
B. Poonen and M. Rubinstein, The number of intersection points made by the diagonals of a regular polygon, arXiv:math/9508209 [math.MG], 19952006, which has fewer typos than the SIAM version.
B. Poonen and M. Rubinstein, Number of Intersection Points Made by the Diagonals of a Regular Polygon, SIAM J. Discrete Mathematics, Vol. 11, pp. 135156 (1998). [Copy on SIAM web site]
B. Poonen and M. Rubinstein, The number of intersection points made by the diagonals of a regular polygon, SIAM J. on Discrete Mathematics, Vol. 11, No. 1, 135156 (1998). [Copy on B. Poonen's web site]
B. Poonen and M. Rubinstein, Mathematica programs for A006561 and related sequences
N. J. A. Sloane, Three (No, 8) Lovely Problems from the OEIS, Experimental Mathematics Seminar, Rutgers University, Oct 05 2017, Part I, Part 2, Slides. (Mentions this sequence)


EXAMPLE

Triangle begins:
0,
0,
0,
0,1,
0,5,
0,12,1,
0,35,
0,40,8,1,
0,126,
0,140,20,0,1,
0,330,
0,...


CROSSREFS

Cf. A006561, A292104 (column k=2).
Sequence in context: A088307 A208477 A007392 * A052401 A222946 A214121
Adjacent sequences: A292102 A292103 A292104 * A292106 A292107 A292108


KEYWORD

nonn,tabf,more


AUTHOR

N. J. A. Sloane, Sep 14 2017


STATUS

approved



