login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Numerator of the harmonic mean of the first n positive Fibonacci numbers.
2

%I #7 Nov 27 2014 17:13:53

%S 1,1,6,24,150,720,1560,87360,1670760,20420400,1999157160,13085392320,

%T 3302971111440,103154328557280,1348374437570160,67598505136850688,

%U 114701988497522458032,2307534121538392979232,10183789060049355548733936

%N Numerator of the harmonic mean of the first n positive Fibonacci numbers.

%H Colin Barker, <a href="/A250743/b250743.txt">Table of n, a(n) for n = 1..120</a>

%e 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.

%o (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]=numerator(n/d)); s

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

%K nonn,frac

%O 1,3

%A _Colin Barker_, Nov 27 2014