OFFSET
1,1
COMMENTS
When n = 2 the graph is the Cartesian product of two double edges.
a(n) is divisible by 2^(n + 1).
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..500
Eric Weisstein's World of Mathematics, Eulerian Cycle
Index entries for linear recurrences with constant coefficients, signature (14, -60, 72).
FORMULA
a(n) = 14*a(n-1) - 60*a(n-2) + 72*a(n-3) for n > 3.
G.f.: 4*x*(1 - 4*x)/((1 - 2*x)*(1 - 6*x)^2).
PROG
(PARI) Vec(4*(1 - 4*x)/((1 - 2*x)*(1 - 6*x)^2) + O(x^30))
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Jan 14 2018
STATUS
approved