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 A143825 #9 Nov 13 2018 00:36:41 %S A143825 1,3,1,4,1,3,5,6,4,3,8,10,5,4,6,7,9,11,5,8,13,6,10,7,2,12,9,2,8,11,2, %T A143825 7,14,10,13,16,9,17,12,18,15,11,20,21,22,24,19,14,13,25,23,12,16,26, %U A143825 27,17,15,30,18,31,28,32,14,20,34,21,19,22,33,16,24,36,15,17,23,25,35,18,37 %N A143825 This sequence displays every positive integer exactly three times; there is one number between the first and second 1's and one number between the second and third 1's; two numbers between the first and second 2's and two numbers between the second and third 2's; ... n numbers between the first and second n's and n numbers between the second and third n's. %C A143825 The sequence displaying every positive integer exactly twice is A026272. Construction method: we always fill the next empty "hole" with the smallest available integer. There is no proof that this sequence could go on forever. Terms computed by Gilles Sadowski. %H A143825 Eric Angelini, <a href="http://www.cetteadressecomportecinquantesignes.com/Kimberlike02.htm">Kimberlike sequences</a> %H A143825 E. Angelini, <a href="/A143825/a143825.pdf">Kimberlike sequences</a> [Cached, with permission] %K A143825 base,nonn %O A143825 1,2 %A A143825 _Eric Angelini_, Sep 02 2008