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A294575 Numbers n such that 2 * A243823(n) > n. 2

%I

%S 144,162,174,186,192,198,200,204,216,220,222,228,230,234,238,240,246,

%T 250,252,258,260,264,266,270,276,280,282,288,290,294,300,306,308,310,

%U 312,318,320,322,324,330,336,340,342,348,350,354,360,364,366,370,372,374

%N Numbers n such that 2 * A243823(n) > n.

%C Consider A243823(n), which is the number of m < n that are products of at least one prime p | n and at least one prime q that does not divide n. These numbers m in the cototient of n do not divide a power of n. This sequence lists numbers n where such numbers m are predominant.

%H Michael De Vlieger, <a href="/A294575/b294575.txt">Table of n, a(n) for n = 1..10000</a>

%e A272619(10) = (6), A243823(10) = 1, so 10 is not in the sequence. A243823(144) = 74, which is greater than half of all numbers less than or equal to 144, thus 144 is the first term.

%t Select[Range[10^3], Function[n, 2 (n - (Count[Range@ n, _?(PowerMod[n, Floor@ Log2@ n, #] == 0 &)] + EulerPhi[n] - 1)) > n]]

%Y Cf. A243823, A272619, A294576.

%K nonn

%O 1,1

%A _Michael De Vlieger_, Nov 17 2017

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Last modified October 26 11:59 EDT 2021. Contains 348267 sequences. (Running on oeis4.)