[seqfan] format of "cons" sequences of decimal expansions

Maximilian Hasler maximilian.hasler at gmail.com
Mon Dec 13 00:01:08 CET 2010

Dear seqfans,

maybe the launch of the new OEIS is an occasion to renew the
discussion about offsets for "cons" sequences
(giving the decimal expansion of constants).

I find the current convention rather confusing,
e.g. for gamma = 0.577...., one has a(0)=5, a(-1)=7, ...
cf http://oeis.org/A001620

If a change can be considered, my suggestion would be to have
increasing indices such that

constant = sum_{n=offset...oo}  a(n)  *10^(-n)
<=> a(n) = constant * 10^n mod 10

For Euler's constant this would yield  a(1) = 5, a(2) = 7, ...

The offset would then give the number of "leading zeros", a negative
offset would correspond to constants >= 10.

I am aware that this would be a major change, especially if there are
many xref's to a given number.
(But I think there are very few instances where the n-th term of the
sequence is refereed to explicitely.)
To make the transition, a possible choice might also be to duplicate,
if necessary in a special case. (Don't know whether this is a good
idea, though.)

Maybe the discussion, and collection of ideas, should take place on
the OEIS wiki, as to avoid that those who are looking for "pure math"
on this list would be disgusted by technical discussions. To this end
I just created
and copied this message into the discussion page.



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