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 A165305 #4 Aug 24 2012 10:50:02 %S A165305 1,2,3,4,5,6,7,12,34,56,71,23,45,67,123,456,712,345,671,234,567,1234, %T A165305 5671,2345,6712,3456,7123,4567,12345,67123,45671,23456,71234,56712, %U A165305 34567,123456,712345,671234,567123,456712,345671,234567,1234567 %N A165305 a(n) is the smallest number not yet in the sequence such that the concatenation of all terms yields a periodic stream of digits 1, 2, 3, ..., 7 (repeat from 1). %e A165305 For a(8), having already 1, 2, 3, 4, 5, 6, 7, the next number must be 12 because after 1,2,3,4,5,6,7 we shall continue with a 1. %e A165305 But 1 is already in the sequence so we need to add a 2 -> 12. And so on. %Y A165305 Cf. A165300-A165304, A165306, A165307 %K A165305 easy,base,nonn %O A165305 1,2 %A A165305 _Paolo P. Lava_ and _Giorgio Balzarotti_, Sep 14 2009 %E A165305 Keyword base added by _R. J. Mathar_, Feb 02 2010