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 A043093 #7 Jul 24 2013 01:36:28 %S A043093 0,1,2,3,4,5,6,7,9,10,11,12,13,14,15,17,18,19,20,21,22,23,25,26,27,28, %T A043093 29,30,31,33,34,35,36,37,38,39,41,42,43,44,45,46,47,50,51,52,53,54,55, %U A043093 63,64,66,67,68,69,70,71,72,74,75,76,77,78 %N A043093 Every string of 2 consecutive base 7 digits contains exactly 2 distinct numbers. %Y A043093 Cf. A000975 (base-2 analog), A031941 or A043089 (base-3 analog), A031942 or A043090 (base-4 analog), A031943 or A043091 (base-5 analog), A043092, ..., A043096 (base-6 through base-10 analog). %K A043093 nonn,base %O A043093 0,3 %A A043093 _Clark Kimberling_