A103957 A nonsense sequence.

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

Offset

0,3

Links

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

Formula

Involves substitutions 1-> {1, 2}, 2->{1, 3}, 3->1.

Mathematica

Hofstadter[n_Integer? Positive] := Hofstadter[n] = Hofstadter[n - Hofstadter[n - 1]] + Hofstadter[n - Hofstadter[n - 2]];
Hofstadter[0] = Hofstadter[1] = 1;
s[1] = {1, 2}; s[2] = {1, 3}; s[3] = {1};
t[a_] := Join[a, Flatten[s /@ a]];
p[0] = {1}; p[1] = t[{1}];
p[n_] := t[p[n - 1]];
Flatten[Table[p[If[n > 0, Hofstadter[n], n]], {n, 0, 7}]]

Crossrefs

Cf. A073058, A103684.

Sequence in context: A233284 A112195 A103956 * A232550 A363851 A305426

Adjacent sequences: A103954 A103955 A103956 * A103958 A103959 A103960

Keyword

nonn,uned,less

Author

Roger L. Bagula, Mar 30 2005

Status

approved