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 A138902 #18 Jun 24 2025 10:37:47 %S A138902 1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, %T A138902 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, %U A138902 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,6,6,6 %N A138902 a(n) = d!, where d is the number of digits in n. %H A138902 James Spahlinger, <a href="/A138902/b138902.txt">Table of n, a(n) for n = 0..10000</a> %F A138902 a(n) = A000142(A055642(n)). - _James Spahlinger_, Oct 09 2012 %t A138902 a[n_]:=IntegerLength[n]!;Array[a,103,0] (* _James C. McMahon_, Jun 24 2025 *) %o A138902 (Haskell) a138902 = a000142 . a055642 -- _James Spahlinger_, Oct 09 2012 %Y A138902 Different from A047726. Cf. A138908. %K A138902 easy,nonn,base %O A138902 0,11 %A A138902 _Odimar Fabeny_, May 16 2008 %E A138902 Edited by _N. J. A. Sloane_, Sep 29 2011, at the suggestion of _Franklin T. Adams-Watters_