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 A226595 #37 Oct 06 2018 04:40:54 %S A226595 0,2,4,7,9,12,15,17,20,24,27,29,33,36,39 %N A226595 Lengths of maximal nontouching increasing paths in n X n grids. %C A226595 The path is not allowed to touch itself, not even on single points. "Increasing" means that the (Euclidean) length of each line segment must be strictly longer than the last. %H A226595 Giovanni Resta, <a href="/A226595/a226595.png">Illustration of a(2)-a(9)</a> %H A226595 Bert Dobbelaere, <a href="/A226595/a226595.txt">C++ program</a> %H A226595 Gordon Hamilton, <a href="https://www.youtube.com/watch?v=ZNmstUbD-pA">$1,000,000 Unsolved Problem for Grade 8</a> (2011) %H A226595 Stan Wagon, <a href="/A226595/a226595_1.pdf">Illustration for a(2)-a(12)</a> %F A226595 a(n) <= A226596(n) <= A160663(n-1). %e A226595 An example for a(8)=17 %e A226595 ------------------------- %e A226595 01 02 . . . . 05 . %e A226595 .. . 03 . 04 . . 18 %e A226595 09 07 . . 06 . . 16 %e A226595 .. . . . . . . 14 %e A226595 .. . . . . . . 12 %e A226595 .. . 08 . . . . . %e A226595 10 17 15 13 . . . . %e A226595 .. . . . 11 . . . %e A226595 ------------------------- %Y A226595 Cf. A226596. %K A226595 nonn,hard,nice,more %O A226595 1,2 %A A226595 _Charles R Greathouse IV_ and _Giovanni Resta_, Jun 13 2013 %E A226595 a(10)-a(12) from Joseph DeVincentis via _Charles R Greathouse IV_, Oct 08 2015 %E A226595 a(13) from _Charles R Greathouse IV_, Oct 25 2015 using code from Joseph DeVincentis %E A226595 a(14)-a(15) from _Bert Dobbelaere_, Oct 05 2018