This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A290167 #28 Sep 18 2017 15:57:32 %S A290167 1,5,121,9598,1679181,453504350,172005077014,86949091994273, %T A290167 56483442337203525,45847249692285567451,45469223124152747878400, %U A290167 54099446571414415140387750,76055371931321606140937295538,124721482827599093214246240617246 %N A290167 Number of complete non-collateral matches with lattice points on the edges of an n X n square (symmetries and rotations excluded). %H A290167 César Eliud Lozada, <a href="/A290167/a290167_1.pdf">Complete matches</a> %H A290167 Andrew Howroyd, <a href="/A290167/a290167.txt">PARI script and formula</a> %e A290167 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. Only 5 of these are not symmetries or reflections of the others, so a(2) = 5. %Y A290167 Cf. A139267 (number of distinct matches), A290166. %K A290167 nonn %O A290167 1,2 %A A290167 _César Eliud Lozada_, Jul 22 2017 %E A290167 a(4) corrected by _César Eliud Lozada_, Sep 15 2017 %E A290167 a(5)-a(8) from _Andrew Howroyd_, Sep 16 2017 %E A290167 a(9)-a(14) from _Andrew Howroyd_, Sep 18 2017