OFFSET
0,2
COMMENTS
Counts closed walks of length 2n at the degree 3 node of the graph of the (7,4) Hamming code. With interpolated zeros, counts paths of length n at this node.
REFERENCES
David J.C. Mackay, Information Theory, Inference and Learning Algorithms, CUP, 2003, p. 19
LINKS
Nathaniel Johnston, Table of n, a(n) for n = 0..500
Index entries for linear recurrences with constant coefficients, signature (8).
FORMULA
G.f.: (1-5*x)/(1-8*x);
a(n) = (3*8^n + 5*0^n)/8.
a(n) = 8*a(n-1) for n > 0. - Harvey P. Dale, Mar 02 2012
MAPLE
seq((3*8^n+5*`if`(n=0, 1, 0))/8, n=0..20); # Nathaniel Johnston, Jun 26 2011
MATHEMATICA
Join[{1}, NestList[8#&, 3, 20]] (* Harvey P. Dale, Mar 02 2012 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Jan 31 2005
STATUS
approved