OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (4,-3).
FORMULA
For n>0, a(n) = 7*3^(n-1) - 1.
G.f.: (1+2*x-x^2)/(1-4*x+3*x^2). [Bruno Berselli, Mar 25 2013]
a(n) = 2*A237930(n-1), n>0. - R. J. Mathar, Jun 24 2020
MATHEMATICA
Join[{1}, Table[7 3^(n-1) - 1, {n, 30}]] (* Vincenzo Librandi, Mar 24 2013 *)
PROG
(Magma) [1] cat [7*3^n-1: n in [0..30]]; // Vincenzo Librandi, Mar 24 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved