This site is supported by donations to The OEIS Foundation.

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A092101 Harmonic primes. 10
 5, 13, 17, 23, 41, 67, 73, 79, 107, 113, 139, 149, 157, 179, 191, 193, 223, 239, 241, 251, 263, 277, 281, 293, 307, 311, 317, 331, 337, 349, 431, 443, 449, 461, 467, 479, 487, 491, 499, 503, 541, 547, 557, 563, 569, 593, 619, 653, 683, 691, 709, 757, 769, 787 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS For p = prime(n), Boyd defines J_p to be the set of numbers k such that p divides A001008(k), the numerator of the harmonic number H(k). For harmonic primes, J_p contains only the three numbers p-1, (p-1)p and (p-1)(p+1). It has been conjectured that there are an infinite number of these primes and that their density in the primes is 1/e. Prime p=A000040(n) is in this sequence iff neither H(k) == 0 (mod p), nor H(k) == -A177783(n) (mod p) have solutions for 1 <= k <= p-2. - Max Alekseyev, May 13 2010 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 David W. Boyd, A p-adic study of the partial sums of the harmonic series, Experimental Math., Vol. 3 (1994), No. 4, 287-302. A. Eswarathasan and E. Levine, p-integral harmonic sums, Discrete Math. 91 (1991), 249-257. PROG (PARI) is(p)=my(K=-Mod((binomial(2*p-1, p)-1)/2/p^3, p), H=Mod(0, p)); for(k=1, p-2, H+=1/k; if(H==0||H==K, return(0))); 1 \\ Charles R Greathouse IV, Mar 16 2014 CROSSREFS Cf. A092102 (non-harmonic primes), A092103 (size of J_p). Sequence in context: A182078 A074278 A087895 * A105596 A037046 A126887 Adjacent sequences:  A092098 A092099 A092100 * A092102 A092103 A092104 KEYWORD nonn AUTHOR T. D. Noe, Feb 20 2004 EXTENSIONS More terms from Max Alekseyev, May 13 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .