A107640 Order of appearance of twos in the tribonacci ( Rauzy type) substitution: triangular.

1, 2, 1, 4, 3, 5, 2, 4, 1, 4, 3, 5, 8, 2, 4, 7, 1, 4, 8, 10, 3, 5, 8, 11, 2, 4, 7, 11, 1, 4, 8, 10, 13, 3, 5, 8, 11, 13, 2, 4, 7, 11, 13, 1, 4, 8, 10, 13, 16, 3, 5, 8, 11, 13, 16, 2, 4, 7, 11, 13, 16, 18, 1, 4, 8, 10, 13, 16, 18, 3, 5, 8, 11, 13, 16, 20

Offset

0,2

Links

Table of n, a(n) for n=0..75.

Formula

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

Mathematica

s[1] = {2}; s[2] = {3}; s[3] = {1, 2, 3}; t[a_] := Flatten[s /@ a]; p[0] =
{1}; p[1] = t[p[0]]; p[n_] := t[p[n - 1]]; a = Table[Flatten[Table[If[(Length[p[i]]) >= j && (p[i][[j]] == 2), j, {}], {j, 1, i}]], {i, 1, 20}]; MatrixForm[a] //Flatten

Crossrefs

Cf. A000073.

Sequence in context: A144334 A141210 A244373 * A030065 A362939 A328676

Adjacent sequences: A107637 A107638 A107639 * A107641 A107642 A107643

Keyword

nonn,uned,tabf

Author

Roger L. Bagula, Jun 09 2005

Status

approved