

A332991


a(n) is the smallest prime power p^k (p prime, k >= 1) such that sum of reciprocals of prime powers up to p^k (prime power harmonic sum) exceeds n.


1




OFFSET

0,1


COMMENTS

The corresponding indices of a(n) in A246655 are 1, 3, 12, 240, ...


LINKS



EXAMPLE

a(1) = 4 because 1/2 + 1/3 = 0.8333... < 1 but 1/2 + 1/3 + 1/4 = 1.0833... > 1.


CROSSREFS

Similar sequences: A002387 (for positive integers), A016088 (for primes), A076751 (for composite numbers), A333004 (for squarefree numbers).


KEYWORD

nonn,hard,more


AUTHOR



EXTENSIONS



STATUS

approved



