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 A109571 #3 Jul 01 2012 12:20:20 %S A109571 1,1,8,1,1,8,1,1,28,1,9,1,1,8,1,1,8,1,1,28,1,9,1,1,8,1,1,8,1,1,28,1, %T A109571 129,1,1,8,1,1,8,1,1,28,1,249,1,1,8,1,1,8,1,1,28,1,9,1,1,8,1,1,8,1,1, %U A109571 28,1,9,1,1,8,1,8,1,1,28,1,129,1,1,8,1,1,8,1,1,28,1,249,1,1,8,1,1,8,1,1,28,1,9 %N A109571 Prague bus clock sequence #2. %C A109571 Start a digital clock at midnight; you read 00:00 (hours and minutes). Wait for 1 minute and read 00:01; if you look at 00:01 in a mirror, you'll see 10:00, which is a sound time on such a clock; wait for another minute and read 00:02; this gives the "mirror time" 20:00, which is sound; you must wait now for 8 minutes before seeing another sound "mirror time": 00:10 gives 01:00; etc. Successive waiting times form the sequence. The "mirror digit transform" is: 0->0, 1->1, 2->5, 5->2 and 8->8. "8" can't be used here and "5" must be carefully placed. %e A109571 Successive number of minutes one has to wait, starting at midnight, to read a sound "mirror" time on a digital clock. %Y A109571 Cf. A028354, A109527. %K A109571 base,easy,fini,nonn %O A109571 1,3 %A A109571 _Eric Angelini_ and others, Aug 30 2005