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%I #16 May 19 2014 15:21:54
%S 36,540,39852,75418035,113570688,120668856,141963360,150836070,
%T 18826510275,37653020550,106746035772831,213492071545662,
%U 2906980416141000,4360470624211500,11118121391391372
%N Numbers n having more than one representation as k*(1+phi(k)/2), where phi(k) is Euler's totient function.
%C The computations were provided by _Robert Israel_ from sci.math. He found no n that had three representations up to k < 10^6. It would be a challenge to find an n with three representations.
%H Math Forum, <a href="http://mathforum.org/kb/message.jspa?messageID=7370315&tstart=0">Topic: a(1+ phi(a)/2) = b(1+phi(b)/2) </a>
%e For 36, sum of the coprimes of 9 is 27, add to 9 to get 36; the sum of the coprimes of 12 is 24, add 12 to 24 to also get 36. The corresponding {a,b} for each term is listed at the sci.math reference.
%K nonn
%O 1,1
%A _J. M. Bergot_, Feb 17 2011
%E a(11)-a(15) from _Donovan Johnson_, Feb 21 2011