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%I #30 Nov 12 2024 12:22:24
%S 1,1,7,103,829,7261,66595,598627,5377849,48426745,435876607,
%T 3922582687,35303534581,317733991381,2859598948507,25736384863003,
%U 231627537879409,2084647743751921,18761829221081335,168856464809568727,1519708183900618669,13677373637498037325
%N Cogrowth sequence of the 16-element group Q8 X C2 = <S,T,U | S^4, T^4, U^2, STS^3T, S^2U^2, [S,U], [T,U]>.
%C Gives the even terms, all the odd terms are 0.
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (8, 2, 72, -81).
%F G.f.: (27*x^3+3*x^2+7*x-1) / ((1-x) * (9*x-1) * (9*x^2+2*x+1)).
%Y Cf. A047854 (D4 X C2), A377840 (C8 X C2), A071930 (Q8).
%K nonn,easy
%O 0,3
%A _Sean A. Irvine_, Nov 10 2024