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) = 9*n - a(n-1) - 4, with n>1, a(1)=7.
G.f.: x*(7 + 2*x^2) / ( (1+x)*(x-1)^2 ). - R. J. Mathar, Jul 10 2011
a(n) = a(n-1) +a(n-2) -a(n-3). - Vincenzo Librandi, Sep 19 2013
E.g.f.: (1/4)*(-9 + 8*exp(x) + (18*x + 1)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 22 2016
MATHEMATICA
Table[7 + 9 Floor[(n - 1)/2], {n, 70}] (* or *) CoefficientList[Series[(7 + 2 x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 19 2013 *)
PROG
(Magma) [7+9*Floor((n-1)/2): n in [1..70]]; // Vincenzo Librandi, Sep 19 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 25 2009
EXTENSIONS
New definition by Vincenzo Librandi, Sep 19 2013
STATUS
approved