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Number of generations for which prime(n) divides A001008(k) for some k.
4

%I #11 May 17 2016 11:38:30

%S 4,3,7,30,3,3,7,3,5,7,4,3,5,5,6,6,4,3,8,3,3

%N Number of generations for which prime(n) divides A001008(k) for some k.

%C For any prime p, generation m consists of the numbers p^(m-1) <= k < p^m. The zeroth generation consists of just the number 0. When there is a k in generation m such that p divides A001008(k), then that k may generate solutions in generation m+1. It is conjectured that for all primes there are solutions for only a finite number of generations. The number of generations is unknown for p=83.

%C Boyd's table 3 states incorrectly that harmonic primes have 2 generations; harmonic primes have 3 generations.

%H David W. Boyd, <a href="http://projecteuclid.org/euclid.em/1048515811">A p-adic study of the partial sums of the harmonic series</a>, Experimental Math., Vol. 3 (1994), No. 4, 287-302.

%H A. Eswarathasan and E. Levine, <a href="http://dx.doi.org/10.1016/0012-365X(90)90234-9">p-integral harmonic sums</a>, Discrete Math. 91 (1991), 249-257.

%e a(4)=7 because the fourth prime, 7, divides A001008(k) for k = 6, 42, 48, 295, 299, 337, 341, 2096, 2390, 14675, 16731, 16735 and 102728. These values of k fall into 6 generations; adding the zeroth generation makes a total of 7 generations.

%Y Cf. A072984 (least k such that prime(n) divides A001008(k)), A092101 (harmonic primes), A092102 (non-harmonic primes).

%K more,nonn

%O 2,1

%A _T. D. Noe_, Feb 24 2004; corrected Jul 28 2004