A290167 -id:A290167 - cp's OEIS frontend

A290166 Number of complete non-collateral matches with lattice points on the edges of an n X n square.

1, 13, 684, 73980, 13376448, 3627115200, 1376014521600, 695592156268800, 451867517982720000, 366777996951376281600, 363753784968105369600000, 432795572570448228556800000, 608442975450529801872998400000, 997771862620790990336507904000000

Offset: 1

César Eliud Lozada, Jul 22 2017

nonn

It appears that an n X n square here refers to a square array of points with n+1 points along each side, so that there are n edges on each side. - N. J. A. Sloane, Aug 22 2017

			Points on the sides of a 2 X 2 square can be matched in 13 different ways, if matching two points on the same side is not allowed. Therefore a(2)=13.

César Eliud Lozada, Complete matches

Cf. A139267 (number of distinct matches), A290167.

\\ s is without corners and left:m-a, right:m-b, top:m-c, bottom:m-d.
s(m,a,b,c,d) = {sum(k=0, m, my(j = k+(a+b-c-d)/2); if(j<0||k<0||2*(m-k)Andrew Howroyd, Sep 05 2017

a(5)-a(14) from Andrew Howroyd, Sep 05 2017

cp's OEIS Frontend

A290166 Number of complete non-collateral matches with lattice points on the edges of an n X n square.

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