OFFSET
1,1
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
a(n) = 11*n - a(n-1) - 1, with n>1, a(1)=5.
G.f.: x*(5 + 11*x - 5*x^2)/((1+x)*(x-1)^2). - Vincenzo Librandi, Sep 19 2013
a(n) = a(n-1) +a(n-2) -a(n-3). - Vincenzo Librandi, Sep 19 2013
From G. C. Greubel, Jul 23 2016: (Start)
a(n) = (22*n + 11*(-1)^n + 9)/4.
E.g.f.: (1/4)*(11 - 20*exp(x) + (22*x + 9)*exp(2*x))*exp(-x). (End)
MATHEMATICA
Table[5 + 11 Floor[n/2], {n, 70}] (* or *) CoefficientList[Series[(5 + 11 x - 5 x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 19 2013 *)
LinearRecurrence[{1, 1, -1}, {5, 16, 16}, 80] (* Harvey P. Dale, Aug 28 2019 *)
PROG
(Magma) [5+11*Floor(n/2): n in [1..70]]; // Vincenzo Librandi, Sep 19 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 26 2009
EXTENSIONS
New definition by Vincenzo Librandi, Sep 19 2013
STATUS
approved