[seqfan] Re: A123712 and A178212

Charles Greathouse charles.greathouse at case.edu
Thu Feb 9 15:11:37 CET 2012

```I have real interest in the underlying general question: what does a
given sequence *mean*?  Or, more specific to your problem: how do we
understand a given sequence, when its definition requires a long chase
through other sequences?

At one point I made a program to list sequences which were defined in
terms of sequences which were defined in terms of other sequences.
But the list was too long to look through... a real pity.

In this specific case I've added a program to the sequence so it can
be analyzed at least somewhat more easily.  But that raises as many
questions as it answers.  Why do we care about the number of nonzero
entries on a given row?  What is the significance of the constant 16?

If the two sequences are distinct perhaps the easiest solution is to
find a term where they differ.

Charles Greathouse
Analyst/Programmer
Case Western Reserve University

On Thu, Feb 9, 2012 at 8:33 AM, Peter Luschny
> What does A123712(n) mean? The definition is:
>
> A123712 Positions in A123709 equal to 16, so that row a(n)
> of triangle A123706 has exactly 16 nonzero terms.
>
> To understand this I have to know that
>
> A123709 a(n) = number of nonzero elements in row n of triangle A123706.
>
> To understand this I have to know that
>
> A123706 Matrix inverse of triangle A010766
>
> To understand this I have to know that
>
> A010766 Triangle of numbers [ n/k ], k=1..n.
>
> Alright, so what does A123712(n) mean, put in colloquial terms?
>
> My motivation comes from comparing A123712 with A178212. Are they equal?
> http://oeis.org/search?q=A123712+A178212
>
> Peter
>
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>
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