A377735 - OEIS

%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