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A198969
(11*9^n-1)/2.
3
5, 49, 445, 4009, 36085, 324769, 2922925, 26306329, 236756965, 2130812689, 19177314205, 172595827849, 1553362450645, 13980262055809, 125822358502285, 1132401226520569, 10191611038685125, 91724499348166129, 825520494133495165
OFFSET
0,1
FORMULA
a(n) = 9*a(n-1)+4. a(n) = 10*a(n-1)-9*a(n-2), n>1.
G.f.: (5 - x)/(1 - 10*x + 9*x^2). - Vincenzo Librandi, Jan 03 2013
MATHEMATICA
CoefficientList[Series[(5 - x)/(1 - 10*x + 9*x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 03 2013 *)
LinearRecurrence[{10, -9}, {5, 49}, 20] (* Harvey P. Dale, Oct 16 2021 *)
PROG
(Magma) [(11*9^n-1)/2: n in [0..20]]
CROSSREFS
Sequence in context: A293841 A351586 A224756 * A155629 A096596 A001079
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 01 2011
STATUS
approved