OFFSET
1,1
REFERENCES
F. Faase, On the number of specific spanning subgraphs of the graphs G X P_n, Ars Combin. 49 (1998), 129-154.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
F. Faase, On the number of specific spanning subgraphs of the graphs G X P_n, Preliminary version of paper that appeared in Ars Combin. 49 (1998), 129-154.
F. Faase, Results from the counting program
Index entries for linear recurrences with constant coefficients, signature (8,8).
FORMULA
a(n) = 8*a(n-1) + 8*a(n-2), n>3.
From Bruno Berselli, Aug 02 2011: (Start)
G.f.: 3*x*(1+2*x)^2/(1-8*x-8*x^2).
For n>1, a(n) = 3*sqrt(3)*sqrt(2^(2*n-7))*((2+sqrt(6))^n-(2-sqrt(6))^n). (End)
PROG
(Magma) i:=[3, 36, 324]; [n le 3 select i[n] else 8*(Self(n-1)+Self(n-2)): n in [1..16]]; // Bruno Berselli, Aug 02 2011
(PARI) a(n)=([0, 1; 8, 8]^(n-1)*[3; 36])[1, 1] \\ Charles R Greathouse IV, Jun 23 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved