Consider the morphism 1->{1,2}, 2->{1,3}, 3->{1}; a(n) is the total number of '3' after n substitutions.

A103685

Consider the morphism 1->{1,2}, 2->{1,3}, 3->{1}; a(n) is the total number of '3' after n substitutions.

Terms

    a(0) =0a(1) =0a(2) =1a(3) =5a(4) =17a(5) =51a(6) =147a(7) =419a(8) =1191a(9) =3383a(10) =9607a(11) =27279a(12) =77455a(13) =219919a(14) =624415a(15) =1772895a(16) =5033759a(17) =14292287a(18) =40579903a(19) =115217983a(20) =327136895a(21) =928835455a(22) =2637230207a(23) =7487852799a(24) =21260161279a(25) =60363694335a(26) =171389837823a(27) =486624896511

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