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A221283
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Number of totients up to 10^n.
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0
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1, 6, 38, 291, 2374, 20254, 180184, 1634372, 15037909, 139847905, 1311179363
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) is about 10^n/n * 2.2655434...^((log log n)^2); see Theorem 1 in the Ford paper for a more precise asymptotic.
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EXAMPLE
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There are 6 totients up to 10: {1 = phi(1), 2 = phi(3), 4 = phi(5), 6 = phi(7), 8 = phi(15), 10 = phi(11)}, so a(1) = 6.
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PROG
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(PARI) a(n)=sum(k=1, 10^n, istotient(k))
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CROSSREFS
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KEYWORD
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nonn,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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