A377855 - OEIS

%I #8 Nov 13 2024 15:33:40

%S 1,0,2,6,40,120,512,2016,8320,32640,131072,523776,2099200,8386560,

%T 33554432,134209536,536903680,2147450880,8589934592,34359607296,

%U 137439477760,549755289600,2199023255552,8796090925056,35184380477440,140737479966720,562949953421312

%N Cogrowth sequence of the 16-element group C4:C4 = <S,T | S^4, T^4, STST^3>.

%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 (2, 4, 8, 32).

%F G.f.: (12*x^4+6*x^3+2*x^2+2*x-1) / ((4*x-1) * (2*x+1) * (4*x^2+1)).

%Y Cf. A070775 (C4 X C4), A377840 (C8 X C2).

%K nonn,easy

%O 0,3

%A _Sean A. Irvine_, Nov 09 2024