OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..92
Henri Lifchitz and Renaud Lifchitz, PRP Records
MATHEMATICA
s = 1; Do[ m = n; s = s + 1/n; If[ PrimeQ[ Numerator[ s ] - Denominator[ s ] ], Print[ n ] ], {n, 2, 2500} ]
hnoQ[n_]:=Module[{h=HarmonicNumber[n]}, PrimeQ[Numerator[h]-Denominator[ h]]]; Select[Range[5000], hnoQ] (* Harvey P. Dale, May 23 2012 *)
PROG
(PARI) for(n=2, 300, if(isprime(lcm(n!, sum(k=2, n, 1/k))/n!), print1(n, ", "))); \\ Arkadiusz Wesolowski, Oct 13 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Sep 28 2001
EXTENSIONS
More terms from Arkadiusz Wesolowski, Oct 13 2011
STATUS
approved