A214640 - OEIS

A214640

A ternary sequence : closed under 1 -> 123, 2 -> 12, 3 -> 2 . Start with 1 .

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

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OFFSET

1,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..10000

EXAMPLE

Start: 1

Rules:

1 --> 123

2 --> 12

3 --> 2

-------------

0: (#=1)

1: (#=3)

123

2: (#=6)

123122

3: (#=13)

1231221231212

4: (#=29)

12312212312121231221231212312

5: (#=64)

1231221231212123122123121231212312212312121231221231212312212312

MAPLE

S:= proc(n) option remember; `if`(n=0, [1], subs(x=[1, 2, 3][],

y=[1, 2][], z=2, subs(1=x, 2=y, 3=z, S(n-1))))

end:

a:= proc(n) local k;

for k while nops(S(k))<n do od; S(k)[n]

end:

seq(a(n), n=1..100); # Alois P. Heinz, Jul 28 2012

MATHEMATICA

SubstitutionSystem[{1 -> {1, 2, 3}, 2 -> {1, 2}, 3 -> {2}}, {1}, 6] // Last (* Jean-François Alcover, Nov 04 2020 *)

CROSSREFS

Cf. A214260, A214641, A214642, A214644.

Sequence in context: A289585 A128864 A106798 * A224965 A194298 A194306

Adjacent sequences: A214637 A214638 A214639 * A214641 A214642 A214643

KEYWORD

nonn,easy

AUTHOR

Philippe Deléham, Jul 23 2012

STATUS

approved