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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
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).
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
KEYWORD
nonn,more
AUTHOR
Ivan Neretin, May 24 2015
STATUS
approved