OFFSET
0,2
LINKS
FORMULA
G.f.: (1-x-x^2)/(1-8*x-x^2).
a(n) = Sum_{k=0..n} A155161(n,k)*7^k. - Philippe Deléham, Feb 08 2012
MAPLE
a:=proc(n) option remember; if n=0 then 1 elif n=1 then 7 elif n=2 then 56 else 8*a(n-1)+a(n-2); fi; end: seq(a(n), n=0..30); # Wesley Ivan Hurt, Jan 28 2017
MATHEMATICA
LinearRecurrence[{8, 1}, {1, 7, 56}, 20] (* or *)
CoefficientList[Series[(1 - x - x^2)/(1 - 8 x - x^2), {x, 0, 19}], x] (* or *)
{1, 7}~Join~Table[Simplify[# (14/17) ((4 + #)^n - (4 - #)^n) + (7/2) ((4 + #)^n + (4 - #)^n) + Mod[Binomial[2 n, n], 2]] &@ Sqrt@ 17, {n, 18}] (* Michael De Vlieger, Jan 30 2017 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Philippe Deléham, Jan 21 2009
STATUS
approved