A125707 Numbers n such that A024528(n) is prime.

1, 2, 3, 4, 5, 7, 14, 15, 17, 23, 32, 36, 42, 309, 1384, 1588

Offset

1,2

Comments

A024528(n) is the numerator of 1 + Sum[ 1/Prime[k], {k,1,n} ], or n-th elementary symmetric function of {1, prime(1), prime(2), ..., prime(n-1)}.

Links

Table of n, a(n) for n=1..16.

Mathematica

f=1; Do[p=Prime[n]; f=f+1/p; g=Numerator[f]; If[PrimeQ[g], Print[{n, p, g}]], {n, 1, 50}]

Crossrefs

Cf. A024528, A109628.

Sequence in context: A268199 A178767 A337188 * A039060 A278442 A092065

Adjacent sequences: A125704 A125705 A125706 * A125708 A125709 A125710

Keyword

hard,more,nonn

Author

Alexander Adamchuk, Feb 01 2007

Extensions

3 more terms from Ryan Propper, Feb 11 2008

Status

approved