OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Charles K. Cook and Michael R. Bacon, Some identities for Jacobsthal and Jacobsthal-Lucas numbers satisfying higher order recurrence relations, Annales Mathematicae et Informaticae, 41 (2013) pp. 27-39.
Index entries for linear recurrences with constant coefficients, signature (1,1,1,1,2).
FORMULA
G.f.: (2*x^4+2*x^3+2*x^2-x+2) / ((1-2*x)*(x^4+x^3+x^2+x+1)). - Colin Barker, Jun 08 2013
MAPLE
f:=proc(n) option remember;
if n=0 then 2 elif n=1 then 1 elif n=2 then 5 elif n=3 then 10 elif n=4 then 20 else
f(n-1)+f(n-2)+f(n-3)+f(n-4)+2*f(n-5); fi; end;
[seq(f(n), n=0..40)];
MATHEMATICA
CoefficientList[Series[-(2 x^4 + 2 x^3 + 2 x^2 - x + 2) / ((2 x - 1) (x^4 + x^3 + x^2 + x + 1)), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 19 2013 *)
LinearRecurrence[{1, 1, 1, 1, 2}, {2, 1, 5, 10, 20}, 20] (* Harvey P. Dale, Jan 20 2015 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Jun 08 2013
STATUS
approved