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%I #7 Sep 20 2012 12:42:19
%S 3,12,1080,18506880,2198278051200,28657168334177779210174055055360000
%N a(n) = smallest m such that sigma(m)/m = n + 1/3.
%C An upper bound for a(7) is a 77-digit number with factorization: 2^35 3^20 5^9 7^3 11 13^2 17 19 23 29 31 37^2 41 61 67 71 73 109 137 409 521 547 1093 36809 368089.
%C An upper bound for a(8) is a 165-digit number that can be found on given link where line begins with 25/3.
%H Walter Nissen and Michel Marcus, <a href="http://upforthecount.com/math/blackf.txt">Extended Table of Abundancies</a>
%e a(1) = 3 because sigma(3)/3 = 4/3 = 1 + 1/3 and 3 is the earliest m such that sigma(m)/m = 1 + 1/3.
%Y Cf. A160320, A088912.
%K nonn
%O 1,1
%A _Michel Marcus_, Sep 19 2012
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