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Consider the sequence {b(m)} of nonprimes; sequence gives values of m where gcd{m, b(m)} increases.
2

%I #3 Mar 30 2012 17:30:27

%S 1,4,6,8,27,30,33,96,100,120,330,335,340,350,355,360,1008,1080,1092,

%T 1116,1122,1128,1134,3059,3066,3073,3080,3087,3094,8408,8424,8440,

%U 8456,8464,8472,23526,23535,24300,64540,64580,64610,64620,64650,64690,64700

%N Consider the sequence {b(m)} of nonprimes; sequence gives values of m where gcd{m, b(m)} increases.

%e a(4) = 8 because eight is the fourth nonprime number and GCD(4,8) > GCD(3,6).

%t r=0; Do[a = GCD[n, n - PrimePi[n] ]; If[a > r, r = a; Print[n]], {n, 1, 10^5} ]

%Y Cf. A058012. Apart from initial term same as A057809.

%K nonn

%O 0,2

%A _Robert G. Wilson v_, Nov 13 2000

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