OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (21,-119,99).
FORMULA
a(n) = (4*11^(n+2)-5*9^(n+2)+1)/80. - Bruno Berselli, Mar 21 2011
a(n) = 20*a(n-1)-99*a(n-2)+1, n>=2. - Vincenzo Librandi, Mar 21 2011
a(n) = 21*a(n-1)-119*a(n-2)+99*a(n-3). - Wesley Ivan Hurt, Mar 27 2015
MAPLE
a:=n->sum((11^(n-j)-9^(n-j))/2, j=0..n): seq(a(n), n=1..17); # Zerinvary Lajos, Jan 12 2007
MATHEMATICA
CoefficientList[Series[1/((1 - x) (1 - 9 x) (1 - 11 x)), {x, 0, 20}], x] (* Wesley Ivan Hurt, Mar 27 2015 *)
LinearRecurrence[{21, -119, 99}, {1, 21, 322}, 20] (* Harvey P. Dale, Jun 07 2022 *)
PROG
(Magma) [(4*11^(n+2)-5*9^(n+2)+1)/80 : n in [0..20]]; // Wesley Ivan Hurt, Mar 27 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved