OFFSET
1,1
COMMENTS
Essentially the same as A168199. - Georg Fischer, Oct 14 2018
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,1,-1).
FORMULA
G.f.: x*(2 + x^2) / ( (1+x)*(x-1)^2 ).
a(n+1) = A016789(floor(n/2)).
a(n) = a(n-1) +a(n-2) -a(n-3). - Vincenzo Librandi, Sep 16 2013
E.g.f.: (1/4)*(-3 + 4*exp(x) + (6*x - 1)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 16 2016
MATHEMATICA
CoefficientList[Series[(2 + x^2) / ((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 16 2013 *)
Table[(6*n - 3*(-1)^n - 1)/4, {n, 1, 50}] (* or *) LinearRecurrence[ {1, 1, -1}, {2, 2, 5}, 50] (* G. C. Greubel, Jul 16 2016 *)
PROG
(Magma) [3*n/2-1/4-3*(-1)^n/4: n in [1..70]]; // Vincenzo Librandi, Sep 16 2013
CROSSREFS
KEYWORD
nonn,easy,less
AUTHOR
Vincenzo Librandi, Nov 21 2009
STATUS
approved