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A052100
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a(n) = lcm(n, phi(n), n - phi(n)).
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1
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0, 2, 6, 4, 20, 12, 42, 8, 18, 60, 110, 24, 156, 168, 840, 16, 272, 36, 342, 120, 252, 660, 506, 48, 100, 1092, 54, 336, 812, 1320, 930, 32, 8580, 2448, 9240, 72, 1332, 3420, 1560, 240, 1640, 420, 1806, 1320, 2520, 6072, 2162, 96, 294, 300, 31008, 2184, 2756
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OFFSET
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1,2
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COMMENTS
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If n is a power of a prime p, then a(n) = n*(p-1). - Robert Israel, May 20 2015
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LINKS
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FORMULA
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For n=p prime, phi(p)=p-1, cototient(p)=p-1, a(p)=p(p-1)=A009262(p).
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EXAMPLE
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For n=72, phi(72)=24, cototient(72)=48, a(72) = lcm(72,24,48) = 144.
For n=255, phi(255)=128, cototient(255)=127, a(255) = lcm(255,128,127) = 4145280.
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MAPLE
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seq(ilcm(n, numtheory:-phi(n), n - numtheory:-phi(n)), n=1..100); # Robert Israel, May 20 2015
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MATHEMATICA
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Table[LCM[n, EulerPhi[n], n - EulerPhi[n]], {n, 53}] (* Ivan Neretin, May 20 2015 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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