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 A092063 Numbers n such that numerator of Sum_{i=1..n} 1/(prime(i)-1) is prime. 6
 2, 3, 4, 7, 8, 15, 19, 21, 22, 25, 26, 31, 34, 45, 46, 52, 65, 69, 79, 85, 89, 98, 102, 122, 137, 149, 181, 195, 210, 220, 316, 325, 340, 385, 436, 466, 497, 934, 972, 1180, 1211, 1212, 1639, 1807, 2075, 2104, 3100 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Note that the definition here is subtly different from that of A092065. Terms a(k) < 1000 correspond to primes. Beyond, numerators are probable primes. Note that A120271(3100) has 2187 digits. - M. F. Hasler, Feb 06 2008 Intersection of A000040 (the primes) and A120271 (numerators of partial sums of 1/(prime(i)-1)). - M. F. Hasler, Feb 06 2008 LINKS EXAMPLE 1/(2-1) + 1/(3-1) = 3/2 and 3 is prime so a(1)=2 MATHEMATICA Position[Accumulate[1/(Prime[Range]-1)], _?(PrimeQ[ Numerator[ #]]&)]//Flatten (* Harvey P. Dale, Oct 16 2016 *) PROG (PARI) f(n)= s=0; for(i=1, n, s=s+1/(prime(i)-1)); return(s); for (i=1, 500, if(isprime(numerator(f(i))), print1(i, ", "))); (PARI) print_A092063( i=0 /* start testing at i+1 */)={local(s=sum(j=1, i, 1/(prime(j)-1))); while(1, while(!ispseudoprime(numerator(s+=1/(prime(i++)-1))), ); print1(i", "))} - M. F. Hasler, Feb 06 2008 CROSSREFS Cf. A092064, A120271. Sequence in context: A116961 A300486 A120611 * A227007 A126850 A007497 Adjacent sequences:  A092060 A092061 A092062 * A092064 A092065 A092066 KEYWORD hard,nonn AUTHOR Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), Feb 20 2004 EXTENSIONS More terms from M. F. Hasler, Feb 06 2008 Edited by T. D. Noe, Oct 30 2008 Corrected by Harvey P. Dale, Oct 16 2016 STATUS approved

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Last modified June 7 01:26 EDT 2020. Contains 334836 sequences. (Running on oeis4.)