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%I #9 Mar 30 2012 18:38:56
%S 1,10,55,161,209,551,649,1079,1189,3401,6049,6319,9701,12151,14279,
%T 14849,25271,34399,40753,51841,64769,85919,150281,158801,193159,
%U 194399,246401,286579,456191,514999,546209,563471,647351,920639,1156609
%N Nonprime numbers n such that (n+1)*Sum_{d|n} 1/(d+1) is an integer.
%C Or, nonprime numbers n such that Sum_{ d dividing n} C(n,d+1)/C(n,d) is an integer.
%t Select[Range[2, 1250000], ! PrimeQ[ # ] && IntegerQ[( # + 1)*Apply[Plus, 1/(Divisors[ # ] + 1)]] & ]
%K easy,nonn
%O 1,2
%A _Benoit Cloitre_, Apr 08 2002
%E Edited and extended by _Robert G. Wilson v_, Apr 30 2002
%E Entry revised by _N. J. A. Sloane_ Apr 09 2007 following suggestions by Ryan Propper and Emeric Deutsch.
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