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 A081503 #10 Oct 03 2014 11:43:04 %S A081503 0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,2,2,2,1,1,1,1,2,2,2,2,2,2,1,2,2,2, %T A081503 2,2,2,2,3,3,2,2,2,2,2,3,3,3,2,2,2,2,3,3,3,2,2,2,2,3,3,3,2,2,2,2,3,3, %U A081503 3,3,2,2,2,3,3,3,3,3,3,2,3,3,3,3,3,3,2,3,3,3,3,3,3,2,3,3,3,3,3,3,2,3,3,3,3 %N A081503 Number of steps to reach a single digit when map in A081502 is iterated. %F A081503 a(n) = O(log n). %e A081503 19 -> 3+9 = 12 -> 3+2 = 5, taking 2 steps, so a(19)=2. %p A081503 A081503 := proc(n) %p A081503 local nitr,a ; %p A081503 nitr := n ; %p A081503 a := 0 ; %p A081503 while nitr > 9 do %p A081503 nitr := A081502(nitr) ; %p A081503 a := a+1 ; %p A081503 end do; %p A081503 a ; %p A081503 end proc: # _R. J. Mathar_, Oct 03 2014 %K A081503 nonn,easy,base %O A081503 0,18 %A A081503 _N. J. A. Sloane_, Apr 22 2003 %E A081503 More terms from _Matthew Conroy_, Jan 16 2006 %E A081503 Formula from _Charles R Greathouse IV_, Aug 02 2010