OFFSET
1,3
COMMENTS
S(2,2,2) is the star graph with three legs of length two.
LINKS
Index entries for linear recurrences with constant coefficients, signature (14,-84,280,-560,672,-448,128).
FORMULA
a(n) = 2^n*C(n,3)*((n-1)^3 - 3*(n-1)).
G.f.: 16*x^3*(1 + 58*x + 116*x^2 + 8*x^3)/(1 - 2*x)^7. - Stefano Spezia, Apr 20 2022
PROG
(Python) from math import comb
def a(n):
return (2**n)*comb(n, 3)*((n-1)**3-3*(n-1))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Ben Eck, Apr 20 2022
STATUS
approved