Uncertain sequences (was Re: TR : Re : The OEIS will be on holiday for the rest of the year!)

[Jaap Spies]

Brendan McKay wrote:
> * N. J. A. Sloane <njas at research.att.com> [060123 03:11]:
> 
>>Jaap Spies says:
>>
>>There is another uncertain factor in the calculations and that is
>>the planetary model. Some calculations use the VSOP 87 model and
>>others depend on the JPL ephemerides from NASA.
>>
>>What policy do you have with sequences that may be changing in time?
> 
>  
> I don't agree that this sequence changes with time.  Only our
> estimate of it changes with time.  There is in fact an algorithm
> for computing it correctly - wait for each event to happen.  This
> is a rather slow algorithm, but an algorithm nevertheless.

By definition: "Exceptional years of 23rd december's winter solstice
since the beginning of the Gregorian Calendar in 1582", there is
one sure entry: 1903. But not in Russia where the Gregorian calendar
was introduced in 1918!

> We can
> present the early terms as certain and later terms as conjectures,
> like we do with many sequences.

Next entries can be conjectured under the assumption of a formula for
DELTA T (which one?) and a model for the solar system (which one?).
Maybe we can ask Jean Meeus, the author of "Astronomical Algorithms",
to do the predictions.

Jaap