A367279 Place n equally spaced points on each side of a square, and join each of these points by a chord to the 3*n new points on the other three sides: sequence gives number of edges in the resulting planar graph.

4, 16, 156, 788, 2880, 6468, 15800, 27828, 49936, 78732, 134656, 173396, 286676, 373004, 495300, 659556, 938328, 1086108, 1525216, 1727060, 2187912, 2724272, 3468932, 3730780, 4781740, 5611000, 6549252, 7404820, 9272476, 9645308, 12278824, 13302464, 15300332, 17565324, 19475404, 20973584

Offset: 0

Author

Scott R. Shannon, Nov 11 2023

Keywords

• nonn

Comments

See A367276 for further information. See A367276 and A367278 for images of the square.

Crossrefs

Cf. A367276 (vertices), A367277 (interior vertices), A367278 (regions).

Formula

a(n) = A367276(n) + A367278(n) - 1 (Euler).