OFFSET
1,1
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
K. Cameron, Thomason's algorithm for finding a second hamiltonian circuit through a given edge in a cubic graph is exponential on Krawczyk's graphs, Discrete Mathematics (235), 2001, pp. 69-77.
Donald Knuth, The Art of Computer Programming, Pre-fascicle 8a, Hamiltonian paths and cycles, exercise 77, pp. 16, 26-27 (retrieved Feb 22 2020).
Index entries for linear recurrences with constant coefficients, signature (4,-1,0,-1,0,-1).
FORMULA
G.f.: 2*z*(3+2*z+z^2-2*z^3) / ((1-z)*(1-3*z-2*z^2-2*z^3-z^4-z^5)).
a(n) = 4*a(n-1) - a(n-2) - a(n-4) - a(n-6) for n>6. - Colin Barker, Feb 22 2020
MATHEMATICA
LinearRecurrence[{4, -1, 0, -1, 0, -1}, {6, 28, 108, 400, 1486, 5516}, 20] (* Jinyuan Wang, Feb 22 2020 *)
PROG
(PARI) Vec(2*z*(3 + 2*z + z^2 - 2*z^3) / ((1 - z)*(1 - 3*z - 2*z^2 - 2*z^3 - z^4 - z^5)) + O(z^30)) \\ Colin Barker, Feb 22 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Filip Stappers, Feb 22 2020
EXTENSIONS
More terms from Jinyuan Wang, Feb 22 2020
STATUS
approved