A250744 -id:A250744 - cp's OEIS frontend

A247240 Numbers such that A059248(k), the numerator of Sum_{i=1..k} 1/Fibonacci(i), is not equal to A250744(k), the denominator of the harmonic mean of the first k positive Fibonacci numbers.

2, 7, 35, 245, 485, 12914

Offset: 1

Michel Marcus, Nov 28 2014

Next term > 20000. - Jinyuan Wang, Feb 14 2020

s=0; lst={}; Do[s+=1/Fibonacci[n]; If[Numerator[s]!=Denominator[n/s], AppendTo[lst, n]], {n, 10000}]; lst (* Jinyuan Wang, Feb 14 2020 *)

a(6) from Jinyuan Wang, Feb 14 2020

A250743 Numerator of the harmonic mean of the first n positive Fibonacci numbers.

Original entry on oeis.org

1, 1, 6, 24, 150, 720, 1560, 87360, 1670760, 20420400, 1999157160, 13085392320, 3302971111440, 103154328557280, 1348374437570160, 67598505136850688, 114701988497522458032, 2307534121538392979232, 10183789060049355548733936

Offset: 1

Colin Barker, Nov 27 2014

			a(4) = 24 because the first 4 positive Fibonacci numbers are [1,1,2,3], and 4/(1/1+1/1+1/2+1/3) = 24/17.

Colin Barker, Table of n, a(n) for n = 1..120

Cf. A000045 (Fibonacci numbers), A250744 (denominators).

s=vector(30); f=Vec(x/(1-x-x^2)+O(x^(#s+1))); n=d=0; for(k=1, #s, n++; d+=1/f[k]; s[k]=numerator(n/d)); s

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A247240 Numbers such that A059248(k), the numerator of Sum_{i=1..k} 1/Fibonacci(i), is not equal to A250744(k), the denominator of the harmonic mean of the first k positive Fibonacci numbers.

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A250743 Numerator of the harmonic mean of the first n positive Fibonacci numbers.

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