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a(n) = smallest number m such that sigma(k) = m has at least n positive solutions k.
1

%I #8 Mar 30 2012 19:00:28

%S 1,12,24,72,72,168,240,336,360,504,576,720,720,720,720,1440,1440,1440,

%T 1440,1440,1440,2880,2880,2880,2880,2880,2880,2880,2880,4320,4320,

%U 4320,4320,4320,4320,5760,5760,8640,8640,8640,8640,8640,8640,8640,8640,8640,8640

%N a(n) = smallest number m such that sigma(k) = m has at least n positive solutions k.

%C Sequence of numbers from A145899.

%e a(6) = 168 because 168 is the smallest value of sigma(k) for n=6 positive integers k such that sigma(k) = 168 has solution; k = 60, 78, 92, 123, 143, 167.

%Y Cf. A085790, A000203, A145899, A206027.

%K nonn

%O 1,2

%A _Jaroslav Krizek_, Feb 03 2012