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 A114315 #9 Sep 23 2014 09:14:49 %S A114315 4,6,8,20,21,24,40,41,44,46,48,52,60,70,80,81,84,86,88,90,102,204,305, %T A114315 476,485,600,649,650,660,664,667,669,686,698,720,934,2030,2040,4100, %U A114315 4680,5000,6010,6011,6014,6016,6018,6040,6044,6046,6048,6060 %N A114315 Self-describing sequence. See the sequence as a succession of digits: then a(n) is the position of a prime digit in the sequence. %C A114315 "Prime" digits are 2, 3, 5 and 7. %e A114315 Prime digits are between brackets: %e A114315 Sequence: 4,6,8,(2)0,(2)1,(2)4,40,41,44,46,48,(5)(2),60,(7)0... %e A114315 Digit pos: 4th 6th 8th 20 21st 24th ... = the sequence itself. %K A114315 base,easy,nonn %O A114315 1,1 %A A114315 _Eric Angelini_, Feb 05 2006 %E A114315 More terms from _Ray G. Opao_, Sep 23 2014