A258255 Least k such that n <= Sum_{i=1..k} 1/A258252(i), where A258252 are the numbers having lowest possible denominators for the sums of reciprocals.

1, 4, 14, 46, 153, 535, 1855, 6449, 22460, 81237

Offset

1,2

Comments

Presumably, every natural number is reached at some step exactly, rather than "stepped over" (as is the case with harmonic series).

Links

Table of n, a(n) for n=1..10.

Example

For the first few terms of A258252, the sums of their reciprocal are: 1, 3/2, 5/3, 2, 9/4, 7/3, 12/5, 5/2, 18/7, 13/5, 14/5, 17/6, 20/7, 3, ... that are equal to 1, 2, 3 for n=1, 4, 14. So a(1)=1, a(2)=4, a(3)=14.

Crossrefs

Cf. A258252, A004080 (analog for harmonic series), A002387.

Sequence in context: A049221 A081670 A297016 * A124805 A362279 A121530

Adjacent sequences: A258252 A258253 A258254 * A258256 A258257 A258258

Keyword

nonn,more

Author

Ivan Neretin, May 24 2015

Status

approved