N. J. A. Sloane njas at research.att.com
Tue Oct 21 23:16:33 CEST 2003

```More about two-valued seqs., and a reply to Roland Bacher:

Superseeker does a pretty good job already with 2-valued sequences

To test this, send it the Thue-Morse sequence with the
values 0 and 1 replaced say by 8 and 9, and
watch what happens!

The following is from the help page for superseeker:

. For a 2-valued sequence,
Superseeker finds the 6 characteristic integer sequences
associated with the sequence
and looks them up in the OEIS

Suppose the sequence takes the values X and Y.  The 6
characteristic sequences, all equivalent to the original, are:

replace X,Y by 1,2; by 2,1;
the positions of the X's, of the Y's;
the run lengths;
and the derivative, i.e. the positions where the sequence changes.

MEMO TO SEQFANS:  it would be very nice if , whenever you are
studying a two-valed sequence in the OEIS, you made
sure that all 6 of the characteristic sequences
associated with it are also in the OEIS!

Maybe someone could do this for all the usual suspects - Thue-Morse,
Moebius, etc.!

Thanks

Neil

```