%I A060630
%S A060630 0,1,10,19,109,149,197,399,694,796,893,897,1167,1579,1596,1667,1790,
%T A060630 1777,2859,1779,1778,1873,3679,5926,11289,9539,13551,4589,5960,12066,
%U A060630 12265,19119,10927,12379,11742,65220,34038,40390,1110025,10100023
%N A060630 For n > 9 let f(n) be formed by writing down the sums of every pair of 
               consecutive digits of n: e.g. f(3469)=71015 because 3+4=7,4+6=10,
               6+9=15; let f(n)=0 if n is a single digit. Sequence gives smallest 
               number requiring n iterations to reach zero.
%C A060630 24-th and 26-th terms are unknown, but a(25)=9539, a(27)=4589 and a(28)=5960.
%H A060630 Erich Friedman, <a href="http://www.stetson.edu/~efriedma/mathmagic/0200.html">
               Problem of the Month (Feb 2000)</a>
%F A060630 a(n)=10^(n-2)+9, for n=2, 3, 4 and for n > 40
%e A060630 a(5)=149 because 149 -(1)-> 513 -(2)-> 64 -(3)-> 10 -(4)-> 1 -(5)-> 0. 
               a(7)=399 because 399 -(1)-> 1218 -(2)-> 339 -(3)-> 612 -(4)-> 73 
               -(5)-> 10 -(6)-> 1 -(7)-> 0.
%Y A060630 Sequence in context: A007811 A166706 A131495 this_sequence A070199 A015445 
               A123001
%Y A060630 Adjacent sequences: A060627 A060628 A060629 this_sequence A060631 A060632 
               A060633
%K A060630 base,nonn
%O A060630 0,3
%A A060630 Jason Earls (zevi_35711(AT)yahoo.com), Apr 14 2001
%E A060630 More terms from Berend Jan van der Zwaag, Jun 23 2001