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 A080913 #6 Mar 30 2012 17:34:50 %S A080913 1,195,525,532,6167,6174,6182,12229008,94219126,94219751 %N A080913 Value of index in A080900 when a number first appears for the n-th time. %e A080913 Terms 181 through 200 of A080900 are 502 507 512 510 515 513 518 523 521 526 531 529 527 525 523 521 519 517 522 527 and at term 195 we see the first duplicate, 523. So a(2) = 195. %Y A080913 Cf. A080900, A080912 (actual records). %K A080913 nonn,more %O A080913 1,2 %A A080913 _N. J. A. Sloane_, Apr 02 2003 %E A080913 One more term from Lambert Herrgesell (zero815(AT)googlemail.com), Mar 09 2007 %E A080913 a(9)-a(10) from _Donovan Johnson_, Sep 24 2009