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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. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A120546 A058966 A058967 * 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

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Last modified September 20 12:13 EDT 2019. Contains 327231 sequences. (Running on oeis4.)