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%I #22 Sep 11 2021 15:12:09
%S 2,2,2,2,2,9,5,12,18,5,22,12,26,14,30,16,34,18,38,20,42,22,46,24,50,
%T 26,54,28,58,30,62,32,66,34,70,36,74,38,78,40,82,42,86,44,90,46,94,48,
%U 98,50,102,52,106,54,110,56,114,58,118,60,122,62,126,64,130
%N Eventual period of a single cell in rule 9 cellular automaton in a cyclic universe of width n.
%C _Bradley Klee_ computed a(1)-a(10).
%D Bradley Klee, Posting to Math Fun Mailing List, Apr 26 2020
%F Conjectures from _Colin Barker_, May 09 2020: (Start)
%F G.f.: x*(2 + 2*x - 2*x^2 - 2*x^3 + 7*x^5 + 3*x^6 - 4*x^7 + 10*x^8 - 10*x^9 - 9*x^10 + 14*x^11 - 5*x^13) / ((1 - x)^2*(1 + x)^2).
%F a(n) = 2*a(n-2) - a(n-4) for n>14.
%F (End)
%F Conjecture: a(n) = (3 - (-1)^n)*n/2 for n > 10. - _Stefano Spezia_, Sep 11 2021
%Y Cf. A180001, A334496, A334499-A334515.
%K nonn
%O 1,1
%A _N. J. A. Sloane_, May 05 2020
%E More terms from _Jinyuan Wang_, May 09 2020
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