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..170
FORMULA
G.f.: x^9/((1-x)*(1-5*x)*(1-25*x)*(1-125*x)*(1-625*x)*(1-3125*x)*(1-15625*x)*(1-78125*x)*(1-390625*x)*(1-1953125*x)). - Vincenzo Librandi, Aug 10 2016
a(n) = Product_{i=1..9} (5^(n-i+1)-1)/(5^i-1), by definition. - Vincenzo Librandi, Aug 10 2016
MATHEMATICA
Table[QBinomial[n, 9, 5], {n, 9, 20}] (* Vincenzo Librandi, Aug 10 2016 *)
PROG
(Sage) [gaussian_binomial(n, 9, 5) for n in range(9, 16)] # Zerinvary Lajos, May 25 2009
(Magma) r:=9; q:=5; [&*[(1-q^(n-i+1))/(1-q^i): i in [1..r]]: n in [r..20]]; // Vincenzo Librandi, Aug 10 2016
(PARI) r=9; q=5; for(n=r, 30, print1(prod(j=1, r, (1-q^(n-j+1))/(1-q^j)), ", ")) \\ G. C. Greubel, Jun 07 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Offset changed by Vincenzo Librandi, Aug 10 2016
STATUS
approved