[seqfan] Re: Question regarding A073216

Richard Guy rkg at cpsc.ucalgary.ca
Sat Oct 8 18:34:39 CEST 2011


It should perhaps be noted that this sequence is A007051
together with its (successive) multiples by (powers of) 3 ?

Best to all,  R.

On Sat, 8 Oct 2011, D. S. McNeil wrote:

>> 1, 2, 3, 5, 6, 9, 14, 15, 18, 27, 41, 42, 45, 54, 81.
>
> [...]
>
>> Question: Assuming the sequence given in the paper is indeed identical to
>> A073216 (to be confirmed)
>
> I think they're the same.  The paper sequence is defined as integers
> of the form c/2 where c has the sum of its base 3 digits being 2, so
> it's the sum of two powers of 3 divided by 2 (either distinct powers,
> looking like 1000100, or nondistinct, like 2000), which is A073216.
>
>> is it legitimate to include a link to the paper in
>> the OEIS entry for the sequence?
>
> Definitely.  Please submit it.  We could probably do with a lot more
> references like this and a lot fewer random walks in symbolic
> expression space..
>
>> PS
>> I notice A055235 is marked 'base' - is this right?
>
> I would say no, and would approve the removal, but this shows why base
> is such a troublesome keyword:
> "sum of two powers of three", to which I wouldn't give the base
> keyword, is exactly equivalent to "has base 3 digitsum of 2", to which
> I would.  Since OEIS entries are sequence-centred and not
> definition-centred, this is a problem.
>
>
> Doug
>
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