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 A226596 #16 Mar 14 2018 03:47:51 %S A226596 0,2,4,7,10,13,16,20,22 %N A226596 Lengths of maximal non-crossing and non-overlapping increasing paths in n X n grids. %C A226596 The path is allowed to touch but not cross itself on single points, but not on segments of any length. "Increasing" means that the (Euclidean) length of each line segment must be strictly longer than the last. %H A226596 Giovanni Resta, <a href="/A226596/a226596.png">Illustration of a(2)-a(9)</a> %H A226596 Gordon Hamilton, <a href="http://www.youtube.com/watch?v=ZNmstUbD-pA">$1,000,000 Unsolved Problem for Grade 8</a> (2011) %F A226596 a(n) <= A160663(n-1). %e A226596 A solution for the case a(8)=20 is %e A226596 ------------------------- %e A226596 01 02 . . . . . 16 %e A226596 .. . 03 . . . . 14 %e A226596 09 . 15 . 05 . . 12 %e A226596 .. . 04 . . . . . %e A226596 .. . 06 13 . 07 . 21 %e A226596 .. . 08 . 11 . . 19 %e A226596 10 . . . . . . 17 %e A226596 20 18 . . . . . . %e A226596 ------------------------- %Y A226596 Cf. A226595. %K A226596 nonn,hard,more %O A226596 1,2 %A A226596 _Charles R Greathouse IV_ and _Giovanni Resta_, Jun 13 2013