%I A031286
%S A031286 0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,2,2,1,1,1,
%T A031286 1,1,1,1,2,2,2,1,1,1,1,1,1,2,2,2,2,1,1,1,1,1,2,2,2,2,2,1,1,1,1,2,2,
%U A031286 2,2,2,2,1,1,1,2,2,2,2,2,2,2,1,1,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2
%N A031286 Additive persistence: number of summations of digits needed to obtain 
               a single digit (the digital root).
%D A031286 M. Gardner, Fractal Music, Hypercards and More Mathematical Recreations 
               from Scientific American, Persistence of Numbers, pp. 120-1; 186-7, 
               W. H. Freeman NY 1992
%D A031286 M. D. Diamond and D. D. Reidpath, A Counterexample to Conjectures by 
               Sloane and Erdos Concerning the Persistence of Numbers, Journal of 
               Recreational Mathematics, 29(2) 89-92 1998.
%H A031286 N. J. A. Sloane, <a href="http://www.research.att.com/~njas/doc/persistence.html">
               The persistence of a number</a>, J. Recreational Math., 6 (1973), 
               97-98.
%H A031286 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               AdditivePersistence.html">Link to a section of The World of Mathematics.</
               a>
%Y A031286 Sequence in context: A060128 A031280 A134870 this_sequence A031276 A098744 
               A025429
%Y A031286 Adjacent sequences: A031283 A031284 A031285 this_sequence A031287 A031288 
               A031289
%K A031286 nonn,base
%O A031286 0,20
%A A031286 Eric Weisstein (eric(AT)weisstein.com)
%E A031286 Corrected by Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 
               05 2009