

A268112


Numbers n such that at least one prime p exists such that p < n and v_p(H_n) >= 3, where v_p(x) is the padic valuation of x and H_i is the ith Harmonic number.


0




OFFSET

1,1


COMMENTS

The corresponding p for 848, 9338 and 10583 is 11.


LINKS

Table of n, a(n) for n=1..4.
C. Krattenthaler and T. Rivoal, On the integrality of the Taylor coefficients of mirror maps, II, Communications in Number Theory and Physics, Volume 3, Number 3 (2009), 555591.


PROG

(PARI) is(n) = forprime(p=1, n1, if(valuation((numerator(sum(i=1, n, 1/i))), p) > 2, return(1))); return(0)


CROSSREFS

Cf. A001008.
Sequence in context: A252253 A247532 A235065 * A194618 A252546 A251257
Adjacent sequences: A268109 A268110 A268111 * A268113 A268114 A268115


KEYWORD

nonn,hard,more


AUTHOR

Felix FrÃ¶hlich, Jan 26 2016


STATUS

approved



