

A082912


Least k such that H(k) > 10^n, where H(k) is the harmonic number Sum_{i=1..k} 1/i.


1




OFFSET

0,1


COMMENTS

"In 1968 John W. Wrench Jr calculated the exact minimum number of terms needed for the series to sum past 100; that number is 15 092 688 622 113 788 323 693 563 264 538 101 449 859 497. Certainly, he did not add up the terms.
"Imagine a computer doing so and suppose that it takes it 10^9 seconds to add each new term to the sum and that we set it adding and let it continue doing so indefinitely. The job will have been completed in not less than 3.5 * 10^17 (American) billion years." Havil.


REFERENCES

Julian Havil, Gamma, Exploring Euler's Constant, Princeton University Press, Princeton and Oxford, 2003, page 23.


LINKS

Table of n, a(n) for n=0..2.
R. Baillie, Fun With Very Large Numbers, arXiv preprint arXiv:1105.3943, 2011
R. P. Boas, Jr. and J. W. Wrench, Jr., Partial sums of the harmonic series, Amer. Math. Monthly, 78 (1971), 864870.
Eric Weisstein's World of Mathematics, Harmonic Number
Lin Zhang, A Likelihood Ratio Test of Independence of Components for Highdimensional Normal Vectors, MS Thesis, Univ. Minnesota, 2013.


FORMULA

H(k) ~= log(k) + Euler's Gamma Constant (A001620) + 1/(2k).
a(n) = A002387(10^n).  Joerg Arndt, Jul 13 2015


MATHEMATICA

f[n_] := Floor[Exp[n  EulerGamma]  1/2] + 1; Table[ f[10^n], {n, 0, 2}]


CROSSREFS

Cf. A002387, A001620.
Sequence in context: A134656 A128122 A082178 * A265013 A083973 A094212
Adjacent sequences: A082909 A082910 A082911 * A082913 A082914 A082915


KEYWORD

nonn,bref


AUTHOR

Robert G. Wilson v, Apr 14 2003


STATUS

approved



