OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (19,-90).
FORMULA
G.f.: 1/(1 - 9*x) + 1/(1 - 10*x).
E.g.f.: exp(9*x) + exp(10*x).
a(n) = 19*a(n-1) - 90*a(n-2), a(1)=2, a(2)=19.
MATHEMATICA
CoefficientList[Series[1/(1-9*x) + 1/(1-10*x), {x, 0, 30}], x]
LinearRecurrence[{19, -90}, {2, 19}, 30] (* Harvey P. Dale, Nov 10 2017 *)
PROG
(Magma) [9^n + 10^n: n in [0..30]];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Feb 06 2013
STATUS
approved