OFFSET
8,2
LINKS
Marko R. Riedel et al., Mathematics Stack Exchange, Trees with maximum degree three and three vertices of degree three.
Index entries for linear recurrences with constant coefficients, signature (4,-4,-4,11,-8,0,8,-11,4,4,-4,1).
FORMULA
G.f.: z^8*(1 - z + 2*z^2)/((1 - z)^7*(1 + z)^3*(1 + z^2)).
Cycle index of edges of Eiffel gadget below is (1/8) (a_1^7 + 2 a_1^5 a_2 + a_1^3 a_2^2 + 2 a_1 a_2^3 + 2 a_1 a_2 a_4).
a(n) ~ n^6/5760. - Stefano Spezia, Jun 16 2022
EXAMPLE
First term counts:
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MAPLE
gf := z^8*(1 - z + 2*z^2)/((1 - z)^7*(1 + z)^3*(1 + z^2)): ser := series(gf, z, 42): seq(coeff(ser, z, n), n = 8..40); # Peter Luschny, Jun 16 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Marko Riedel, Jun 15 2022
STATUS
approved