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 A201881 #9 Jul 13 2013 12:04:19 %S A201881 1,1,2,2,1,1,1,3,3,1,4,4,1,2,2,1,1,1,2,1,2,3,1,1,3,2,5,1,1,2,1,5,2,2, %T A201881 2,6,1,1,1,1,1,2,3,3,2,1,3,1,1,1,1,1,6,2,1,2,1,1,2,2,3,1,1,4,4,1,2,1, %U A201881 1,2,2,2,1,3,1,4,1,1,2,1,1,1,1,7,3,2 %N A201881 Run lengths in maximally unpredictable sequences A007061, A038219. %C A201881 a(2*n-1) = length of n-th block of consecutive ones in A007061, or consecutive zeros in A038219; %C A201881 a(2*n) = length of n-th block of consecutive twos in A007061, or consecutive ones in A038219; %C A201881 a(A201882(n)) = n and a(m) < n for m < A201882(n). %H A201881 Reinhard Zumkeller, <a href="/A201881/b201881.txt">Table of n, a(n) for n = 1..1000</a> %e A201881 A007061: 1, 2, 1,1, 2,2, 1, 2, 1, 2,2,2, 1,1,1, 2, 1,1,1,1, 2,2,2,2, .. %e A201881 A038219: 0, 1, 0,0, 1,1, 0, 1, 0, 1,1,1, 0,0,0, 1, 0,0,0,0, 1,1,1,1, .. %e A201881 A201881: 1, 1, __2, __2, 1, 1, 1, ____3, ____3, 1, ______4, ______4, ... %o A201881 (Haskell) %o A201881 import Data.List (group) %o A201881 a201881 n = a201881_list !! (n-1) %o A201881 a201881_list = map length $ group a007061_list %K A201881 nonn %O A201881 1,3 %A A201881 _Reinhard Zumkeller_, Dec 11 2011