A250744 Denominator of the harmonic mean of the first n positive Fibonacci numbers.

1, 1, 5, 17, 91, 379, 721, 35849, 614893, 6800951, 607326679, 3651532639, 851897554247, 24724573280923, 301787157353771, 14188276949397301, 22662903194758542865, 430644772287132696121, 1800653989272587268758525, 369150309888695460837999593

Offset: 1

Author

Colin Barker, Nov 27 2014

Keywords

• nonn
• frac

Comments

Similar to A059248. - Michel Marcus and Colin Barker, Nov 28 2014

Examples

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

Links

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

Crossrefs

Cf. A000045 (Fibonacci numbers), A250743 (numerators).

Cf. A059248.

Programs

Mathematica

Module[{nn=20,f},f=Fibonacci[Range[nn]];Table[HarmonicMean[Take[f,n]],{n,nn}]]//Denominator (* Harvey P. Dale, Aug 31 2020 *)

PARI

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]=denominator(n/d)); s