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

1,1

Comments

A216766 is the numerators of the partial sums of 1/A216765(n).

Links

Amiram Eldar, Table of n, a(n) for n = 1..420

Formula

a(n) = denominator(Sum_{k=1..n} 1/A216765(k)).

Example

 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, ...

Mathematica

Denominator[FoldList[Plus, 1/(1 + Select[Range[250], GCD @@ FactorInteger[#][[;; , 2]] > 1 &])]] (* Amiram Eldar, May 05 2022 *)

Crossrefs

Cf. A001597, A045542, A175064, A214390, A214391, A216765, A216766 (numerators).

Sequence in context: A345398 A341383 A214711 * A288320 A003185 A302276

Adjacent sequences: A216764 A216765 A216766 * A216768 A216769 A216770

Keyword

nonn,easy,frac

Author

Jonathan Vos Post, Sep 16 2012

Status

approved