OFFSET
0,2
COMMENTS
A semicircular polygon with 2n+2 points is created by placing n+2 equally spaced vertices along the semicircle's arc (including the two end vertices). Also place n+2 equally spaced vertices along the diameter (again including the same two end vertices). Now connect every pair of vertices by a straight line segment. The sequence gives the number of regions in the resulting figure.
LINKS
Lars Blomberg, Table of n, a(n) for n = 0..50
Scott R. Shannon, Illustration for n = 2.
Scott R. Shannon, Illustration for n = 3.
Scott R. Shannon, Illustration for n = 5.
Scott R. Shannon, Illustration for n = 10.
Scott R. Shannon, Illustration for n = 15.
Scott R. Shannon, Illustration for n = 20.
CROSSREFS
KEYWORD
nonn
AUTHOR
Scott R. Shannon and N. J. A. Sloane, Mar 26 2020
EXTENSIONS
a(21) and beyond from Lars Blomberg, May 01 2020
STATUS
approved