OFFSET
1,1
COMMENTS
The second row of the array A059503.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (6,-11,6,-1).
FORMULA
G.f.: x*(2 - 7*x + 6*x^2 - x^3)/(1 - 3*x + x^2)^2.
From G. C. Greubel, Sep 10 2017: (Start)
a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3) - a(n-4).
a(n) = ((3 - n)*Fibonacci(2*n) + (5 + 3*n)*Fibonacci(2*n - 1))/5. (End)
MATHEMATICA
LinearRecurrence[{6, -11, 6, -1}, {2, 5, 14, 40}, 50] (* or *) Rest[CoefficientList[Series[x*(2 - 7*x + 6*x^2 - x^3)/(1 - 3*x + x^2)^2, {x, 0, 50}], x]] (* G. C. Greubel, Sep 10 2017 *)
PROG
(PARI) x='x+O('x^50); Vec(x*(2-7*x+6*x^2-x^3)/(1-3*x+x^2)^2) \\ G. C. Greubel, Sep 10 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Floor van Lamoen, Jan 19 2001
STATUS
approved