A106581 Alternating two level four-symbol substitution: characteristic polynomial: x^2*(x^2-3).

2, 4, 3, 1, 2, 2, 2, 4, 3, 1, 4, 3, 1, 4, 3, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3

Offset

0,1

Comments

A triangle shaped digraph with one central point. Triangular levels as: {2}, {4, 3, 1}, {2, 2, 2}, {4, 3, 1, 4, 3, 1, 4, 3, 1}, {2, 2, 2, 2, 2, 2, 2, 2, 2}, {4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3, 1, 4, 3,1, 4, 3,1}, {2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,2, 2, 2,2}

Links

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

Formula

1->{2}, 2->{4, 3, 1}, 3->{2}, 4->{2}.

Mathematica

s[1] = {2}; s[2] = {4, 3, 1}; s[3] = {2}; s[4] = {2};
t[a_] := Flatten[s /@ a];
p[0] = {2}; p[n_] := t[p[n - 1]];
Table[p[i], {i, 0, 7}]//Flatten

Crossrefs

Sequence in context: A134893 A227862 A229802 * A317612 A070402 A125941

Adjacent sequences: A106578 A106579 A106580 * A106582 A106583 A106584

Keyword

nonn,uned

Author

Roger L. Bagula, May 09 2005

Status

approved