OFFSET
8,2
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 = 8..150
FORMULA
a(n) = Product_{i=1..8} (7^(n-i+1)-1)/(7^i-1), by definition. - Vincenzo Librandi, Aug 06 2016
G.f.: x^8/((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)). - Ilya Gutkovskiy, Aug 06 2016
MATHEMATICA
Drop[QBinomial[Range[0, 20], 8, 7], 8] (* Harvey P. Dale, Mar 26 2013 *)
PROG
(Sage) [gaussian_binomial(n, 8, 7) for n in range(8, 15)] # Zerinvary Lajos, May 25 2009
(Magma) r:=8; q:=7; [&*[(1-q^(n-i+1))/(1-q^i): i in [1..r]]: n in [r..20]]; // Vincenzo Librandi, Aug 06 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
One additional term, offset corrected, Harvey P. Dale, Mar 26 2013
STATUS
approved