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A096625 Denominators of the Riemann prime counting function. 2
1, 1, 1, 2, 2, 2, 2, 6, 3, 3, 3, 3, 3, 3, 3, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..74.

Eric Weisstein's World of Mathematics, Riemann Prime Counting Function

EXAMPLE

0, 1, 2, 5/2, 7/2, 7/2, 9/2, 29/6, 16/3, 16/3, 19/3, ...

MATHEMATICA

Table[Sum[PrimePi[x^(1/k)]/k, {k, Log2[x]}], {x, 100}] // Denominator (* Eric W. Weisstein, Jan 09 2019 *)

PROG

(PARI) a(n) = denominator(sum(k=1, n, if (p=isprimepower(k), 1/p))); \\ Michel Marcus, Jan 07 2019

(PARI) a(n) = denominator(sum(k=1, logint(n, 2), primepi(sqrtnint(n, k))/k)); \\ Daniel Suteu, Jan 07 2019

CROSSREFS

Cf. A096624.

Sequence in context: A119462 A293221 A334512 * A263455 A283677 A260983

Adjacent sequences:  A096622 A096623 A096624 * A096626 A096627 A096628

KEYWORD

nonn,frac

AUTHOR

Eric W. Weisstein, Jul 01 2004

STATUS

approved

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Last modified August 7 19:57 EDT 2020. Contains 336279 sequences. (Running on oeis4.)