OFFSET
0,1
FORMULA
1->(2), 2->{3}, 3->{1, 2, 3}, a(n) = order of appearance of threes in the substitution
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]] pp = p[12] a = Flatten[Table[If[pp[[j]] == 3, j, {}], {j, 1, Length[pp]}]]
CROSSREFS
KEYWORD
nonn,uned
AUTHOR
Roger L. Bagula, Jun 11 2005
STATUS
approved