OFFSET
9,2
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 = 9..140
FORMULA
G.f.: x^9/((1-x)*(1-7*x)*(1-49*x)*(1-343*x)*(1-2401*x)*(1-16807*x)*(1-117649*x)*(1-823543*x)*(1-5764801*x)*(1-40353607*x)). - Vincenzo Librandi, Aug 12 2016
a(n) = Product_{i=1..9} (7^(n-i+1)-1)/(7^i-1), by definition. - Vincenzo Librandi, Aug 12 2016
MATHEMATICA
Table[QBinomial[n, 9, 7], {n, 9, 20}] (* Vincenzo Librandi, Aug 12 2016 *)
PROG
(Sage) [gaussian_binomial(n, 9, 7) for n in range(9, 17)] # Zerinvary Lajos, May 25 2009
(Magma) r:=9; q:=7; [&*[(1-q^(n-i+1))/(1-q^i): i in [1..r]]: n in [r..20]]; // Vincenzo Librandi, Aug 12 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Offset changed by Vincenzo Librandi, Aug 12 2016
STATUS
approved