

A092065


Numbers n such that numerator of Sum_{k=1..n} 1/(prime(k)k) is prime.


2



2, 3, 4, 5, 7, 14, 21, 22, 26, 27, 32, 43, 51, 58, 62, 65, 82, 131, 148, 207, 229, 249, 257, 320, 334, 386, 423, 440, 481, 747, 823, 1181, 1314, 1915, 2025, 2269
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OFFSET

1,1


COMMENTS

Note that the definition here is subtly different from that of A092063.


LINKS

Table of n, a(n) for n=1..36.


MAPLE

count:= 0:
S:= 0: p:= 0;
for n from 1 to 2500 do
p:= nextprime(p);
S:= S + 1/(p  n);
if isprime(numer(S)) then
count:= count+1;
A[count]:= n;
fi
od:
seq(A[i], i=1..count); # Robert Israel, Sep 07 2014


MATHEMATICA

f=0; Do[ p=Prime[n]; f=f+1/(pn); g=Numerator[f]; If[ PrimeQ[g], Print[n]], {n, 1, 500} ]


PROG

(PARI) S=1; for(n=2, 100, S=S+1/(prime(n)n); if(isprime(numerator(S)), print1(n, ", "))) \\ Edward Jiang, Sep 08 2014


CROSSREFS

Cf. A092066.
Sequence in context: A125707 A039060 A278442 * A044955 A044817 A297136
Adjacent sequences: A092062 A092063 A092064 * A092066 A092067 A092068


KEYWORD

nonn


AUTHOR

Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), Feb 20 2004; corrected Apr 24 2006


EXTENSIONS

Sequence and Mathematica program corrected by Alexander Adamchuk, Jul 29 2007
a(30)a(34) from Vincenzo Librandi, Nov 26 2012
a(35) and a(36) from Robert Israel, Sep 07 2014


STATUS

approved



