OFFSET
4,2
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 = 4..200
FORMULA
a(n) = Product_{i=1..4} (9^(n-i+1)-1)/(9^i-1), by definition. - Vincenzo Librandi, Aug 04 2016
MATHEMATICA
Table[QBinomial[n, 4, 9], {n, 4, 20}] (* Vincenzo Librandi, Aug 04 2016 *)
PROG
(Sage) [gaussian_binomial(n, 4, 9) for n in range(4, 15)] # Zerinvary Lajos, May 27 2009
(Magma) r:=4; 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