A334459 -id:A334459 - cp's OEIS frontend

A333519 Number of regions in a polygon whose boundary consists of n+2 equally spaced points around a semicircle and n+2 equally spaced points along the diameter (a total of 2n+2 points). See Comments for precise definition.

0, 2, 13, 48, 141, 312, 652, 1160, 1978, 3106, 4775, 6826, 9803, 13328, 17904, 23536, 30652, 38640, 48945, 60300, 74248, 89892, 108768, 128990, 153826, 180206, 211483, 245000, 284375, 325140, 374450, 425312, 484168, 545938, 616981, 690132, 775077, 862220

Offset: 0

Scott R. Shannon and N. J. A. Sloane, Mar 26 2020

nonn

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.

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.

Cf. A007678, A290865, A255011, A332953, A333282, A334458, A334459.

a(21) and beyond from Lars Blomberg, May 01 2020

A334458 Number of vertices in a polygon whose boundary consists of n+2 equally spaced points around a semicircle and n+2 equally spaced points along the diameter (a total of 2n+2 points). See Comments for precise definition.

Original entry on oeis.org

1, 4, 12, 39, 125, 271, 609, 1076, 1884, 2950, 4642, 6541, 9607, 12969, 17505, 23034, 30294, 37888, 48488, 59404, 73506, 88779, 108077, 127412, 153000, 178514, 210366, 242961, 283243, 322120, 373147, 422454, 482442, 542604, 615300, 685885, 773189, 857791

Offset: 0

Lars Blomberg, May 01 2020

nonn

Lars Blomberg, Table of n, a(n) for n = 0..50

Cf. A333519, A334459

cp's OEIS Frontend

A333519 Number of regions in a polygon whose boundary consists of n+2 equally spaced points around a semicircle and n+2 equally spaced points along the diameter (a total of 2n+2 points). See Comments for precise definition.

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