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 A168234 #3 Mar 30 2012 18:52:04 %S A168234 3,3,13,13,13,13,13,13,13,13,39,39,39,39,39,39,39,39,39,39,39,39,39, %T A168234 39,39,39,39,39,89,89,89,89,89,89,89,89,89,89,89,89,89,89,89,89,89,89, %U A168234 89,89,89,89,89,89,89,89,89,89,89,89,89,89,171,171,171,171,171,171,171 %N A168234 A138100(n) + A168142(n). %C A168234 A138100 counts upwards in blocks of 2*k^2 numbers, restarting from 1,5,21,57,.. = A166464(k-1) = (2*k+1)*(2*k^2-4*k+3)/3, k>=1. %C A168234 A168142 counts downwards in blocks of 2*k^2 numbers, restarting from 2*k^2, k>=1. %C A168234 In consequence, the sequence here contains 2*k^2 copies of the number 1+2*k*(1+2*k^2)/3 = 1+A035597(k), k>=1, %C A168234 where the sequence A035597 is a bisection of A168380. %Y A168234 Cf. A134984, A138725, A168208. %K A168234 nonn,less %O A168234 1,1 %A A168234 _Paul Curtz_, Nov 21 2009 %E A168234 Edited by _R. J. Mathar_, Feb 15 2010