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 A077509 #5 Dec 05 2013 19:55:53 %S A077509 1,3,1,1,33,7,1,63,3,17,51,51,19,3,33,61,59,91,1,119,31,73,59,103,11, %T A077509 41,13,37,11,7,13,141,43,53,23,3,223,17,21,379,17,91,169,27,61,107, %U A077509 141,273,131,77,93,119,23,171,47,51,183,11,381,73,13,21,133,19,119,567,383,83 %N A077509 a(n) = (n+1)*10^d - A077508(n) where d = n - number of digits in n. %e A077509 a(6) = 700000 - 699967 = 33. %Y A077509 Cf. A077504, A077508. %K A077509 base,nonn %O A077509 2,2 %A A077509 _Amarnath Murthy_, Nov 08 2002 %E A077509 More terms from _Sascha Kurz_, Jan 04 2003