OFFSET
11,2
REFERENCES
F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier-North Holland, 1978, p. 698.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 11..200
FORMULA
G.f.: x^11/((1-x)*(1-3*x)*(1-9*x)*(1-27*x)*(1-81*x)*(1-243*x)*(1-729*x)*(1-2187*x)*(1-6561*x)*(1-19683*x)*(1-59049*x)*(1-177147*x)). - Vincenzo Librandi, Aug 11 2016
a(n) = Product_{i=1..11} (3^(n-i+1)-1)/(3^i-1), by definition. - Vincenzo Librandi, Aug 11 2016
MATHEMATICA
Table[QBinomial[n, 11, 3], {n, 11, 20}] (* Vincenzo Librandi, Aug 11 2016 *)
PROG
(Sage) [gaussian_binomial(n, 11, 3) for n in range(11, 20)] # Zerinvary Lajos, May 28 2009
(Magma) r:=11; q:=3; [&*[(1-q^(n-i+1))/(1-q^i): i in [1..r]]: n in [r..20]]; // Vincenzo Librandi, Aug 11 2016
(PARI) r=11; q=3; for(n=r, 30, print1(prod(j=1, r, (1-q^(n-j+1))/(1-q^j)), ", ")) \\ G. C. Greubel, May 30 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Offset changed by Vincenzo Librandi, Aug 11 2016
STATUS
approved