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 A232244 #7 Nov 22 2013 17:44:52 %S A232244 1,2,3,4,3,2,1,2,3,4,3,2,1,2,3,4,5,6,5,4,3,2,3,4,5,6,7,6,5,4,3,2,1,0, %T A232244 1,2,3,4,5,6,7,8,9,8,7,6,5,4,3,2,1,0,1,2,3,4,5,6,7,8,8,7,6,5,4,3,2,1, %U A232244 0,1,2,3,4,5,6,7,8,8,7,6,5,4,3,2,3,4,3 %N A232244 A walk based on the digits of sqrt(2) (A002193). %C A232244 sqrt(2)= 1. 41421354237... %C A232244 Between 1 and 4 we place 2 and 3. %C A232244 Between 4 and 1 we place 3 and 2. %C A232244 Between 1 and 4 we place 2 and 3. %C A232244 Between 4 and 2 we place 3 and so on. %C A232244 This gives: %C A232244 1, 2, 3, 4, 3, 2, 1, 2, 3, 4, 3, 2, 1, 2, 3, ... %C A232244 This could be called a walk (or promenade) on the digits of sqrt(2). %H A232244 Reinhard Zumkeller, <a href="/A232244/b232244.txt">Table of n, a(n) for n = 1..10000</a> %o A232244 (Haskell) %o A232244 a232244 n = a232244_list !! (n-1) %o A232244 a232244_list = 1 : concat (zipWith w a002193_list $ tail a002193_list) %o A232244 where w v u | v > u = [v - 1, v - 2 .. u] %o A232244 | v < u = [v + 1 .. u] %o A232244 | otherwise = [v] %o A232244 -- _Reinhard Zumkeller_, Nov 22 2013 %Y A232244 Cf. A002193. %K A232244 nonn,easy,base %O A232244 1,2 %A A232244 _Philippe Deléham_, Nov 20 2013 at the suggestion of _N. J. A. Sloane_