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 A075000 #17 Feb 09 2018 21:48:10
%S A075000 1,6,41,864,2469,20576,493827,7098637639,13717421,1234567891,
%T A075000 82737383012865106529,10288065758426,3513762316247164732,
%U A075000 563643651522439401227280,8230452606740808761
%N A075000 Smallest number such that n*a(n) is a concatenation of n consecutive integers; or 0 if no such number exists.
%C A075000 Conjecture: For every n there exists a nonzero a(n).
%H A075000 Robert G. Wilson v, <a href="/A075000/b075000.txt">Table of n, a(n) for n = 1..100</a>
%F A075000 a(n) = A077306(n)/n. - _Amarnath Murthy_, Nov 03 2002
%e A075000 a(11) = 82737383012865106529 as 11*82737383012865106529 = 910111213141516171819 is the concatenation of 11 numbers from 9 to 19.
%t A075000 f[ n_ ] := Block[ {id = Range@n}, While[ k = FromDigits@ Flatten@ IntegerDigits@ id/n; !IntegerQ@k, id++ ]; k ]; Array[ f, 16 ] (* _Robert G. Wilson v_, Oct 19 2007 *)
%Y A075000 Cf. A074991, A074992, A074993, A074994, A074995, A074996, A036377, A073086, A074999, A075001.
%K A075000 base,nonn
%O A075000 1,2
%A A075000 _Amarnath Murthy_, Aug 31 2002
%E A075000 More terms from _Rick L. Shepherd_, Sep 03 2002