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Numbers m such that sigma(m) is not a nontrivial power, i.e., sigma(m) = A000203(n) is not equal a^b where a and b are greater than 1.
1

%I #12 Dec 20 2021 02:42:31

%S 1,2,4,5,6,8,9,10,11,12,13,14,15,16,17,18,19,20,23,24,25,26,27,28,29,

%T 30,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,

%U 54,55,56,57,58,59,60,61,62,63,64,65,67,68,69,71,72,73,74,75,76,77,78,79

%N Numbers m such that sigma(m) is not a nontrivial power, i.e., sigma(m) = A000203(n) is not equal a^b where a and b are greater than 1.

%C Complement of A065496.

%C A175432(a(n)) = 1 for n >= 1.

%e Number 3 is not in the sequence because sigma(3) = 4 = 2^2.

%Y Cf. A000203, A065496, A175432.

%K nonn

%O 1,2

%A _Jaroslav Krizek_, May 10 2010

%E Extended by _Ray Chandler_, Aug 20 2010