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Periods of sum of squares of digits iterated until the sequence becomes periodic.
18

%I #11 Dec 20 2012 16:52:49

%S 1,1,8,8,8,8,8,1,8,8,1,8,8,1,8,8,8,8,8,1,8,8,8,1,8,8,8,8,1,8,8,1,1,8,

%T 8,8,8,8,8,8,8,8,8,8,1,8,8,8,8,1,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,

%U 1,8,1,8,8,8,8,8,8,8,8,1,8,8,1,8,8,8,1,8,8,8,8,1,8,8,1,8,8,1,8,8

%N Periods of sum of squares of digits iterated until the sequence becomes periodic.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Digitaddition.html">Digit addition.</a>

%Y Cf. A003132, A099645. [From _R. J. Mathar_, May 31 2009]

%K nonn,base

%O 0,3

%A _Eric W. Weisstein_

%E The value a(0)=1 was added by _R. J. Mathar_, May 31 2009