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URL: https://oeis.org/A125708

⇱ A125708 - OEIS

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A125708
Numbers k such that A115963(k) is prime.
0
3, 5, 9, 43, 150, 300, 516, 1254
OFFSET
1,1
COMMENTS
A115963(n) is the numerator of Sum_{k=1..n} 1/prime(k)^3.
a(9) > 5000. - Michael S. Branicky, Aug 04 2024
MATHEMATICA
f=0; Do[p=Prime[n]; f=f+1/p^3; g=Numerator[f]; If[PrimeQ[g], Print[{n, p, g}]], {n, 1, 50}]
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Alexander Adamchuk, Feb 01 2007, Mar 01 2007
EXTENSIONS
a(6) from Alexander Adamchuk, Sep 16 2010
a(7)-a(8) from Amiram Eldar, Feb 18 2019
STATUS
approved