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Let spm(n) be the sum of all prime factors of n counted with multiplicities (A001414); sequence gives numbers n such that spm(n+spm(n)) divides both n and n+spm(n).
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%I #4 Mar 31 2012 10:22:32

%S 60,70,240,2079,2408,2928,3000,3125,4250,6748,15560,19018,19805,22448,

%T 24508,28560,29412,31416,33160,39347,43868,44268,46025,53928,55298,

%U 70438,78387,80236,81655,91238,94800,96824,106134,117952

%N Let spm(n) be the sum of all prime factors of n counted with multiplicities (A001414); sequence gives numbers n such that spm(n+spm(n)) divides both n and n+spm(n).

%e Take 60, having sum of prime factors 2+2+3+5=12 and add that 12 to 60 to get 72, having the sum of its prime factors 2+2+2+3+3=12. We see that this 12 divides both 60 and 72.

%e For 2408, the sum of prime factors is 2+2+2+7+43=56, added to 2408 gives 2464, with sum of prime factors being 2+2+2+2+2+7+11=28; this 28 divides both 2408 and 2464.

%K nonn

%O 1,1

%A _J. M. Bergot_, Aug 27 2007

%E Edited by _Olivier GĂ©rard_, Sep 27 2007