OFFSET
2,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 2..200
Index entries for linear recurrences with constant coefficients, signature (91, -819, 729).
FORMULA
G.f.: 1/[(1-x)(1-9x)(1-81x)].
a(n) = Product_{i=1..2} (9^(n-i+1)-1)/(9^i-1), by definition. - Vincenzo Librandi, Aug 04 2016
MATHEMATICA
Table[QBinomial[n, 2, 9], {n, 2, 20}] (* Vincenzo Librandi, Aug 04 2016 *)
PROG
(Sage) [gaussian_binomial(n, 2, 9) for n in range(2, 16)] # Zerinvary Lajos, May 28 2009
(Magma) r:=2; q:=9; [&*[(1-q^(n-i+1))/(1-q^i): i in [1..r]]: n in [r..20]]; // Vincenzo Librandi, Aug 04 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Offset changed by Vincenzo Librandi, Aug 04 2016
STATUS
approved