Math Questions: A096216 & A116537

Matthew Conroy jumbo at
Sat Apr 1 03:38:11 CEST 2006

On Mar 30, 2006, at 9:30 AM, Leroy Quet wrote:
> Sequence A096216 is (paraphrasing the official name of the sequence):
> a(1)=1, a(n) = the number of earlier terms of the sequence which are
> coprime to n.
> First, is A096216 such that a(2n) is always <= to both a(2n+1) and
> a(2n-1)?

No: a(106)=40>37=a(105).

Smallest n's for which a(2n)>a(2n-1) are 53,1733,2048,2468,2888,2993.
Smallest n's for which a(2n)>a(2n+1) are 1732,2467,2677,2887,3202,3217.

> Also, it SEEMS like the limits, where {a(k)} is either sequence,
> (1/n^2) * sum{k=1 to n} a(k), as n -> inf,
> approaches one of two nonzero finite constants, the constant  
> depending on
> which sequence is {a(k)}.

Let A(n) = 1/n^2*sum(k=1 to n) a(k), for a(k) the sequence A096216.
A(10) = 0.3
A(100) = 0.2653

It certainly doesn't seem to be converging too fast.  Perhaps it's not
converging at all.  Note that A(100000)-A(10000) is almost the same
size as A(10000)-A(1000).

The first 100,000 terms are in this file:


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