OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Index entries for linear recurrences with constant coefficients, signature (1,1,-1).
FORMULA
a(n) = 6*n - a(n-1) - 6 for n>1, a(1)=3.
G.f.: 3*x*(1 + x^2)/((1+x)*(1-x)^2). - Bruno Berselli, Nov 06 2011
a(n) = -a(-n+1) = 3*A109613(n-1) = A198392(n-1) - A198392(-n). - Bruno Berselli, Nov 06 2011 - Sep 17 2013
E.g.f.: (3/2)*(-1 + 2*exp(x) + (2*x - 1)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 18 2016
MATHEMATICA
LinearRecurrence[{1, 1, -1}, {3, 3, 9}, 80 ] (* Vincenzo Librandi, Nov 15 2011 *)
Table[(3/2) (2 n - (-1)^n - 1), {n, 70}] (* Bruno Berselli, Sep 17 2013 *)
PROG
(Magma) [(3/2)*(2*n-(-1)^n-1): n in [1..70]]; // Vincenzo Librandi, Nov 15 2011
CROSSREFS
KEYWORD
nonn,easy,less
AUTHOR
Vincenzo Librandi, Nov 23 2009
EXTENSIONS
New definition by Bruno Berselli, Sep 17 2013
STATUS
approved