A360517 - OEIS

%I #16 Feb 27 2023 22:52:08

%S 0,24,480,18816,1175040,107796480,13630955520,2273062256640,

%T 483283797147648,127601594573783040,40960778432654868480,

%U 15710045049427958169600,7095139411569155034316800,3726944074638630907382071296,2252901869996867025766994411520,1552830650080006456164417892515840

%N Number of 2-color vertex orderings of the labeled cycle graph on 2*n vertices.

%C Bouwer and Star give a recurrence.

%D Bouwer, I., and Z. Star. "A question of protocol." The American mathematical monthly 95.2 (1988): 118-121. See C(n).

%H Andrew Howroyd, <a href="/A360517/b360517.txt">Table of n, a(n) for n = 1..200</a>

%F a(n) = 4*n*(n - 1)*(2*n - 1)*A360514(2*n - 3) for n > 1. - _Andrew Howroyd_, Feb 27 2023

%o (PARI) \\ Needs A360514seq from A360514.

%o seq(n) = {my(v=A360514seq(2*n-1)); vector(n, n, if(n>1, 4*n*(n-1)*(2*n-1)*v[2*n-3]))} \\ _Andrew Howroyd_, Feb 27 2023

%Y Cf. A360514, A360515, A360516.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Feb 27 2023.

%E Terms a(6) and beyond from _Andrew Howroyd_, Feb 27 2023