[seqfan] Secondary offset of zero

[Doug Bell]

I asked this question on the wiki Offsets talk page
<https://oeis.org/wiki/Talk:Offsets#Why_not_use_0_for_the_secondary_offset_when_all_terms_are_-1.2C_0.2C_or_1.3F>,
but given that nobody apparently has that page watch-listed, perhaps this
is a better place to get visibility.

Why not use 0 for the secondary offset when all terms are -1, 0, or 1?

Currently there is no way from the secondary offset to distinguish between
sequences where the first term is not -1, 0, or 1 and sequences where *all*
the terms *are* -1, 0, or 1.

-Doug Bell