A216767 Denominators of partial sums of 1/A216765(n).
5, 45, 90, 1530, 9945, 278460, 3063060, 113333220, 566666100, 566666100, 23233310100, 2346564320100, 143140423526100, 15904491502900, 2051679403874100, 59498702712348900, 59498702712348900, 11721244434332733300, 363358577464314732300
Offset: 1
Examples
The partial sums are of the sequence of fractions: 1/5 + 1/9 + 1/10 + 1/17 + 1/26 + 1/28 + 1/33 + 1/37 + 1/50, ... and thus the partial sums are 1/5, 14/45, 37/90, 719/1530, 5056/9995, 151513/278460, 1759463/3063060, 68163191/113333220, 352149277/566666100, 360867217/566666100, 15078888947/23233310100, ...
Links
- Amiram Eldar, Table of n, a(n) for n = 1..420
Programs
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Mathematica
Denominator[FoldList[Plus, 1/(1 + Select[Range[250], GCD @@ FactorInteger[#][[;; , 2]] > 1 &])]] (* Amiram Eldar, May 05 2022 *)
Formula
a(n) = denominator(Sum_{k=1..n} 1/A216765(k)).
Comments