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Maximum cycle length (orbit size) in the rotation permutation of n+2 side polygon triangularizations.
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%I #14 Jun 20 2024 23:12:44

%S 1,1,2,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,

%T 27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,

%U 50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68

%N Maximum cycle length (orbit size) in the rotation permutation of n+2 side polygon triangularizations.

%C I.e., in permutations A057161 and A057162 (also A057503 and A057504), the longest cycle among all cycles between the (A014138(n-2)+1)-th and (A014138(n-1))-th terms.

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).

%F a(0)=1, a(1)=1, a(2)=2, a(n)=n+2.

%F From _Chai Wah Wu_, Jul 28 2022: (Start)

%F a(n) = 2*a(n-1) - a(n-2) for n > 4.

%F G.f.: (-2*x^4 + 2*x^3 + x^2 - x + 1)/(x - 1)^2. (End)

%o (PARI) a(n)=if(n>2,n+2,1) \\ _Charles R Greathouse IV_, Jun 20 2024

%Y Cf. A057542, A057543, A057545.

%K nonn,easy

%O 0,3

%A _Antti Karttunen_, Sep 07 2000

%E More terms from _Sean A. Irvine_, Jun 13 2022