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A248817
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Numbers that are equal to the arithmetic derivative of their cototient.
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1
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12, 32, 44, 332, 5103, 10935, 12555, 59049, 69255, 94041, 185895, 1114641, 1265625, 1453125, 3639916, 8015625, 10475212, 10521657, 12254625, 21515625, 146484375, 155649627, 178598385, 244603436, 362087739, 1408107267, 1540368225, 2186172700, 2490234375
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OFFSET
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1,1
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COMMENTS
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Solutions of the equation n = (n - phi(n))’.
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LINKS
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EXAMPLE
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Cototient of 12 is 12 - phi(12) = 12 - 4 = 8 and the arithmetic derivative of 8 is 12.
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MAPLE
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with(numtheory); P:= proc(q) local a, n, p; for n from 1 to q do
a:=(n-phi(n))*add(op(2, p)/op(1, p), p=ifactors(n-phi(n))[2]);
if n=a then print(n); fi; od; end: P(10^6);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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