A377735 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]>.

1, 1, 7, 103, 829, 7261, 66595, 598627, 5377849, 48426745, 435876607, 3922582687, 35303534581, 317733991381, 2859598948507, 25736384863003, 231627537879409, 2084647743751921, 18761829221081335, 168856464809568727, 1519708183900618669, 13677373637498037325

Offset

0,3

Comments

Gives the even terms, all the odd terms are 0.

Links

Table of n, a(n) for n=0..21.

Index entries for linear recurrences with constant coefficients, signature (8, 2, 72, -81).

Formula

G.f.: (27*x^3+3*x^2+7*x-1) / ((1-x) * (9*x-1) * (9*x^2+2*x+1)).

Crossrefs

Cf. A047854 (D4 X C2), A377840 (C8 X C2), A071930 (Q8).

Sequence in context: A142400 A032460 A267234 * A246914 A274670 A188946

Adjacent sequences: A377732 A377733 A377734 * A377736 A377737 A377738

Keyword

nonn,easy

Author

Sean A. Irvine, Nov 10 2024

Status

approved