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A057859
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Number of residue classes modulo n which contain a prime.
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5
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1, 2, 3, 3, 5, 4, 7, 5, 7, 6, 11, 6, 13, 8, 10, 9, 17, 8, 19, 10, 14, 12, 23, 10, 21, 14, 19, 14, 29, 11, 31, 17, 22, 18, 26, 14, 37, 20, 26, 18, 41, 15, 43, 22, 26, 24, 47, 18, 43, 22, 34, 26, 53, 20, 42, 26, 38, 30, 59, 19, 61, 32, 38, 33, 50, 23, 67, 34, 46
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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EXAMPLE
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a(30) = 11 since 30k+m can be prime if m = 2, 3 or 5 (once each with k = 0) or m = 1, 7, 11, 13, 17, 19, 23 or 29 (each for an infinite number of values of k).
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MAPLE
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with(numtheory):
a:= n-> phi(n)+nops(factorset(n)):
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MATHEMATICA
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Table[EulerPhi[n] + PrimeNu[n], {n, 1, 100}] (* G. C. Greubel, May 13 2017 *)
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PROG
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(PARI) for(n=1, 100, print1(eulerphi(n) + omega(n), ", ")) \\ G. C. Greubel, May 13 2017
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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