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A377946
Cogrowth sequence of the 16-element group C2^2:C4 = <S,T | S^4, T^2, (ST)^2, (S^2T)^2>.
0
1, 1, 2, 10, 40, 136, 512, 2080, 8320, 32896, 131072, 524800, 2099200, 8390656, 33554432, 134225920, 536903680, 2147516416, 8589934592, 34359869440, 137439477760, 549756338176, 2199023255552, 8796095119360, 35184380477440, 140737496743936, 562949953421312
OFFSET
0,3
COMMENTS
Gives the even terms, all the odd terms are 0.
Also called K8:C2. Gap identifier 16, 3.
FORMULA
G.f.: (12*x^4-14*x^3+8*x^2-5*x+1) / ((4*x-1) * (2*x-1) * (4*x^2+1)).
CROSSREFS
Cf. A377855 (C4:C4), A054879 (C2^3), A377843 (C4 X C2^2), A377943 (C4 o D4).
Sequence in context: A244376 A009338 A261473 * A174395 A320526 A193519
KEYWORD
nonn,easy
AUTHOR
Sean A. Irvine, Nov 11 2024
STATUS
approved