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 A078206 #9 Mar 08 2015 19:37:29 %S A078206 1,126,123264,12340776,1234553367,123456631959,12345677303863, %T A078206 1234567810050426,123456789137345679,1234567891008671105551, %U A078206 1234567891011073225118178,123456789101112073716778055751 %N A078206 Smallest multiple of the concatenation of n down to 1 that begins with the concatenation of 1 up to n. %H A078206 Robert Gerbicz, May 09 2008, <a href="/A078206/b078206.txt">Table of n, a(n) for n = 1..17</a> %e A078206 a(3) = 123264 = 321*384. %o A078206 (PARI) A=B=0;e=f=0;U=1;for(n=1,17,if(n==U,U*=10;f++);A=U*A+n;B+=n*10^e;e+=f; T=1;C=A;while((-C)%B>=T,T*=10;C*=10);print1(C+(-C)%B",")) \\ _Robert Gerbicz_, May 09 2008 %Y A078206 Cf. A078207. %K A078206 base,nonn %O A078206 1,2 %A A078206 _Amarnath Murthy_, Nov 22 2002 %E A078206 More terms from _Robert Gerbicz_, May 09 2008