A108121 A three-symbol substitution sequence with characteristic polynomial: x^3-x^2-2*x-1.

3, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 1, 2, 2, 3, 2, 3, 3, 1, 2, 2, 3, 3, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 1, 2, 2, 3, 2, 3, 3, 1, 2, 2, 3, 3, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 1, 2, 2, 3, 2, 3, 3, 1, 2, 2, 3, 3, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 1, 2

Offset

0,1

Comments

This substitution is unique in that it gives a two part tile that only tiles aperiodically.

Links

Table of n, a(n) for n=0..104.

Formula

1->{2}, 2->{3}, 3->{1, 2, 2, 3}

Mathematica

s[1] = {2}; s[2] = {3}; s[3] = {1, 2, 2, 3}; t[a_] := Flatten[s /@ a]; p[0] = {1}; p[1] = t[p[0]]; p[n_] := t[p[n - 1]] aa = p[8]

Crossrefs

Sequence in context: A085247 A003016 A328848 * A161916 A072548 A079399

Adjacent sequences: A108118 A108119 A108120 * A108122 A108123 A108124

Keyword

nonn,uned

Author

Roger L. Bagula, Jun 04 2005

Status

approved