Start with the word 1234, repeatedly append the words obtained via the maps 1 -> 12, 2 -> 13, 3 -> 42, 4 -> 43.
(history;
published version)
Discussion
Wed Jul 14
03:11
Joerg Arndt: Bagula's links and reference tend to have little to do with the sequence at hand.
LINKS
J. P. Allouche, <a href="https://doi.org/10.1063/1.531916">Schrödinger operators with Rudin-Shapiro potentials are not palindromic</a>, J. Math. Phys. 38 (1997), no. 4, 1843-1848.
Discussion
Tue Jul 13
20:55
Kevin Ryde: I'll have the courage of my convictions and remove. (Paper is referred to in A020987 and A292077 which are among the cases considered.)
20:58
Kevin Ryde: Incidentally Balchin and Rust are also only a brief touch on the morphism part of here, as far as I can tell, but they specifically refer to here, so keep.
Discussion
Tue Jul 13
09:09
Michel Marcus: if kept then it should be J.-P. Allouche
LINKS
Kevin Ryde, <a href="http://user42.tuxfamily.org/seq-A073057-append-morphism/index.html">PARI/GP Code and Notes</a>.
CROSSREFS
Cf. A100260 (morphism as 0..3).
Discussion
Tue Jul 13
08:25
Kevin Ryde: Jean-Paul Allouche reference is only a brief appearance of the morphism (section III "sigma"), on the way to Golay-Rudin-Shapiro. In particular it's not about expand and append like here. I'd be tempted to drop it.
LINKS
Scott Balchin and Dan Rust, <a href="httphttps://www.emiscs.amsuwaterloo.orgca/journals/JIS/VOL20/Rust/rust3.html">Computations for Symbolic Substitutions</a>, Journal of Integer Sequences, Vol. 20 (2017), Article 17.4.1.
Discussion
Fri Jul 03
14:55
OEIS Server: https://oeis.org/edit/global/2859
Discussion
Tue Feb 27
03:36
Joerg Arndt: IMO the reference could go, Bagula's delusional babbling nonwithstanding. I'll leave them, though.