[seqfan] Inconsistency in offset guidelines on the Wiki

[Sidney Cadot]

Hi all,

Concerning the second number in the "offset" field of OEIS entries, the
Wiki is not entirely consistent.

http://oeis.org/wiki/Style_Sheet#Offset says:

"There is a second part to the offset after a comma, which is the 1-based
index of the first term which is greater than 1 in absolute value. *If all
terms are -1, 0, or 1 the second part should be 1*."

However, http://oeis.org/wiki/Offsets says this:

"If there are no terms with absolute value greater than 1, this second
number is *sometimes omitted *(see, e.g., A038219) *and otherwise entered
as 1*."

(Emphasis mine in both cases).

>From inspection of the entire database, it seems that the first convention
is mostly followed.

I think the guideline should be unambiguous, so sequences that are provably
constrained to values {-1, 0, 1} have no second offset value, -OR- they
have a "1" offset. What should it be?

It would also be useful to precisely pin down what to do in some other
corner cases. There's at least four:

(A) we know that the values exceed |a(n)| > 1 at some n, but n is bigger
than the sequence values listed in either the A-file or the b-file. Current
practice is to list such n as the second offset number if it is known; for
example, A216280, A216284.

(B) We know that |a(n)| will exceed 1 at some known index n, but n is too
big to reasonably put in the entry's "offset" field, e.g. if it has a
zillion digits. I know no examples, but they could exist.

(C) We know that |a(n)| will exceed 1 at some point, but the first value is
not currently known.

(D) We do not know whether |a(n)| will exceed 1 at some point.

This is perhaps a bit of a "how-many-angels-can-fit-on-the-head-of-a-pin"
discussion, but since OEIS is striving for an encyclopedic quality
standard, I think it's best to be precise in matters like these.

Best, Sidney