General Sequence Submission Advice

Frank Ellermann nobody at
Sun Oct 26 16:36:17 CET 2003

Chuck Seggelin wrote:

> Set 1: f(x) =3D y (and assume y is never 0)
> Set 2: f(x) gives no result
> A0001: a(n) =3D f(n) or 0 where f(n) gives no result.

That should be okay, if you don't have too many 0s in the
listed terms.  IIRC there's even a sequence in the database,
where -1 indicates "no value", but that's a pain with the
actual database layout for signed sequences.

> As Three Sequences:
> A0001: a(n) =3D The n'th number m where f(m) gives a result.
> A0002: a(n)=3Df(A0001(n)).
> A0003: a(n) =3D The n'th number m where f(m) gives no result.

I'm not sure about your A00003 idea, why not use something
like 1 =3D defined, 0 =3D undefined (or vice versa) ?

> the use of zero as a "signal value" in the former makes me a
> little nervy because at a glance it implies f(n)=3D0 for
> certain n's upon which f() is not applicable.

It's not unusual, and you could add some extra comments and
examples to emphasize it.
                          HTH, bye, Frank

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