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A377885
Cogrowth sequence of the 16-element quasihedral group SD16 = <S,T | S^8, T^2, STS^5T>.
2
1, 1, 1, 4, 28, 136, 544, 2080, 8128, 32512, 130816, 524800, 2099200, 8390656, 33550336, 134201344, 536854528, 2147516416, 8590065664, 34359869440, 137438691328, 549754765312, 2199022206976, 8796095119360, 35184380477440, 140737496743936, 562949936644096
OFFSET
0,4
COMMENTS
Gives the even terms, all the odd terms are 0.
Also called QD16, Q8:C2. Gap identifier 16,8.
FORMULA
G.f.: (6*x^3-7*x^2+5*x-1) / ((4*x-1) * (4*x^2-2*x+1)).
CROSSREFS
Cf. A047849 (D4), A007582 (D8), A071930 (Q8), A377840 (C8 X C2), A377883 (M4(2)).
Sequence in context: A296638 A270721 A367015 * A270892 A271603 A139736
KEYWORD
nonn,easy
AUTHOR
Sean A. Irvine, Nov 10 2024
STATUS
approved