OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..200
Eric Weisstein's World of Mathematics, Ore's Conjecture
EXAMPLE
The sequence of harmonic means starts 1 < 4/3 < 3/2 < 12/7, increasing from the first to the fourth, which adds 1 to 4 to the sequence.
The fifth harmonic mean is 5/3, smaller than 12/7 and not a record, so 5 is not in the sequence.
MAPLE
hm := proc(n) option remember; n* numtheory[tau](n)/numtheory[sigma](n) ; end proc:
A179971 := proc(n) option remember; if n = 1 then 1; else for k from procname(n-1)+1 do if hm(k) > hm(procname(n-1)) then return k; end if; end do; end if; end proc:
seq(A179971(n), n=1..40) ; # R. J. Mathar, Aug 06 2010
MATHEMATICA
f[n_] := f[n] = DivisorSigma[0, n]/Plus @@ (1/Divisors@n); k = 1; mx = 0; lst = {}; While[k < 18480, a = f@k; If[a > mx, mx = a; AppendTo[lst, k]]; k++ ]; lst
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Aug 04 2010
EXTENSIONS
Definition rephrased by R. J. Mathar, Aug 06 2010
STATUS
approved