Christopher N. Swanson - cp's OEIS frontend

User: Christopher N. Swanson

Christopher N. Swanson has authored 2 sequences.

A243643 Number of non-degenerate parallelograms in an n X n permutation array.

0, 0, 0, 6, 62, 362, 1266, 3692, 8904, 19376, 38144, 70574, 122478, 203722, 324554, 500868, 749128, 1094204, 1560240, 2183562, 2998598, 4055502, 5402450, 7107528, 9233488, 11870016, 15100040, 19037586, 23787678, 29495558, 36290898, 44354248, 53846392, 64985376

Offset: 1

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

nonn

A non-degenerate parallelogram has positive area.

Christopher N. Swanson, Randy Ho, Bill Correll, Jr., Table of n, a(n) for n = 1..1000
Mathematics Stack Exchange, Counting non-degenerate parallelograms in permutation arrays

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.

Original entry on oeis.org

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

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

nonn

Configuration of points forms a degenerate parallelogram.

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

Cf. A243643.

cp's OEIS Frontend

User: Christopher N. Swanson

A243643 Number of non-degenerate parallelograms in an n X n permutation array.

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