OFFSET
0,2
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (9).
FORMULA
G.f.: (1-7*x)/(1-9*x).
a(n) = 9*a(n-1) for n>1.
a(n) = 2*9^(n-1) for n>0.
From Amiram Eldar, May 08 2023: (Start)
Sum_{n>=0} 1/a(n) = 25/16.
Sum_{n>=0} (-1)^n/a(n) = 11/20.
Product_{n>=1} (1 - 1/a(n)) = A132025. (End)
MATHEMATICA
CoefficientList[Series[(1-7x)/(1-9x), {x, 0, 20}], x] (* or *) Join[ {1}, NestList[9#&, 2, 20]] (* Harvey P. Dale, Oct 15 2017 *)
PROG
(PARI) Vec((1-7*x)/(1-9*x) + O(x^30))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Mar 18 2016
STATUS
approved