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A198960
3*9^n-1.
1
2, 26, 242, 2186, 19682, 177146, 1594322, 14348906, 129140162, 1162261466, 10460353202, 94143178826, 847288609442, 7625597484986, 68630377364882, 617673396283946, 5559060566555522, 50031545098999706, 450283905890997362
OFFSET
0,1
FORMULA
a(n) = 2*A096053(n).
a(n) = 9*a(n-1)+8, n>0.
a(n) = 10*a(n-1)-9*a(n-2), n>1.
G.f.: 2*(1 + 3*x)/(1 - 10*x + 9*x^2). - Vincenzo Librandi, Jan 03 2013
MATHEMATICA
CoefficientList[Series[2*(1 + 3*x)/(1 - 10*x + 9*x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 03 2013 *)
PROG
(Magma) [3*9^n-1: n in [0..20]]
CROSSREFS
Sequence in context: A211319 A121768 A280556 * A289263 A296600 A187252
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 01 2011
STATUS
approved