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A198967
10*9^n-1.
1
9, 89, 809, 7289, 65609, 590489, 5314409, 47829689, 430467209, 3874204889, 34867844009, 313810596089, 2824295364809, 25418658283289, 228767924549609, 2058911320946489, 18530201888518409, 166771816996665689, 1500946352969991209
OFFSET
0,1
FORMULA
a(n) = 9*a(n-1)+8. a(n) = 10*a(n-1)-9*a(n-2), n>1.
G.f.: (9 - x)/(1 - 10*x + 9*x^2). - Vincenzo Librandi, Jan 03 2013
MATHEMATICA
CoefficientList[Series[(9 - x)/(1 - 10*x + 9*x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 03 2013 *)
PROG
(Magma) [10*9^n-1: n in [0..20]]
(PARI) a(n)=10*9^n-1 \\ Charles R Greathouse IV, Jul 05 2024
CROSSREFS
Sequence in context: A064616 A133486 A224760 * A320093 A015584 A072256
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 01 2011
STATUS
approved