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A199761
(9*11^n+1)/5.
1
2, 20, 218, 2396, 26354, 289892, 3188810, 35076908, 385845986, 4244305844, 46687364282, 513561007100, 5649171078098, 62140881859076, 683549700449834, 7519046704948172, 82709513754429890, 909804651298728788, 10007851164286016666
OFFSET
0,1
FORMULA
a(n) = 11*a(n-1)-2.
a(n) = 12*a(n-1)-11*a(n-2).
G.f.: 2*(1-2*x)/((1-x)*(1-11*x)).
MATHEMATICA
(9*11^Range[0, 20]+1)/5 (* or *) LinearRecurrence[{12, -11}, {2, 20}, 20] (* Harvey P. Dale, Mar 13 2024 *)
PROG
(Magma) [(9*11^n+1)/5: n in [0..30]];
CROSSREFS
Sequence in context: A000906 A308945 A356853 * A214769 A227337 A127110
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 10 2011
STATUS
approved