A234471 Number of sets of 4 distinct collinear points in an n X n permutation array in which leftmost pair has same spacing as rightmost pair.

0, 0, 0, 2, 10, 30, 86, 180, 344, 624, 1056, 1626, 2522, 3646, 5118, 7164, 9784, 12868, 16848, 21438, 27202, 34298, 42550, 51800, 63184, 76256, 91032, 108086, 127850, 149442, 174902, 202552, 233608, 268512, 306664, 349394, 398226, 450510, 507038, 569204

Offset

1,4

Comments

Configuration of points forms a degenerate parallelogram.

Links

Chris Swanson, Randy Ho, Bill Correll, Jr, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A243643.

Sequence in context: A058966 A058967 A355775 * A196317 A318579 A064932

Adjacent sequences: A234468 A234469 A234470 * A234472 A234473 A234474

Keyword

nonn

Author

Christopher N. Swanson, Randy Ho, and Bill Correll, Jr., Jun 08 2014

Status

approved