A140335
Smallest number greater than a(n-1) that, when adding the reciprocals of all the terms up to it, the sum is <= 3.
Original entry on oeis.org
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 230, 57960
Offset: 1
11 does not qualify for the term after 10 because the sum of the reciprocals of the first 11 terms would then fall between 3.01 and 3.02.
A306349
Number of terms in the greedy Egyptian fraction representation of n.
Original entry on oeis.org
1, 4, 13, 35, 99
Offset: 1
a(3)=13 is the number of terms of A140335;
a(4)=35 is the number of terms of A281873.
A323725
a(n) is the last (and thus largest) denominator of an Egyptian fraction representing n, where each consecutive denominator is as small as possible.
Original entry on oeis.org
1, 6, 57960, 36802906522516375115639735990520502954652700
Offset: 1
a(3) = 57960 because (1/1) + (1/2) + (1/3) + (1/4) + (1/5) + (1/6) + (1/7) + (1/8) + (1/9) + (1/10) + (1/15) + (1/230) + (1/57960) = 3 and the final and greatest denominator is 57960. (Sequence A140335 has the full list of denominators.)
A140335 and
A281873 are the denominatorial sequences for 3 and 4, respectively.
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a(n)={my(s=n,k=1); while(s>1/k, s-=1/k; k++); while(s!=0, k=ceil(1/s); s-=1/k); k} \\ Andrew Howroyd, Sep 01 2019
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from sympy import egyptian_fraction
def A323725(n): return egyptian_fraction((n,1))[-1] # Pontus von Brömssen, Aug 03 2020
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