OFFSET
12,2
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 = 12..150
FORMULA
G.f.: x^12/((1-x)*(1-4*x)*(1-16*x)*(1-64*x)*(1-256*x)*(1-1024*x)*(1-4096*x)*(1-16384*x)*(1-65636*x)*(1-262144*x)*(1-1048576*x)*(1-4194304*x)*(1-16777216*x)). - Vincenzo Librandi, Aug 10 2016
a(n) = Product_{i=1..12} (4^(n-i+1)-1)/(4^i-1), by definition. - Vincenzo Librandi, Aug 10 2016
MATHEMATICA
Table[QBinomial[n, 12, 4], {n, 12, 20}] (* Vincenzo Librandi, Aug 10 2016 *)
PROG
(Sage) [gaussian_binomial(n, 12, 4) for n in range(12, 19)] # Zerinvary Lajos, May 28 2009
(Magma) r:=12; q:=4; [&*[(1-q^(n-i+1))/(1-q^i): i in [1..r]]: n in [r..20]]; // Vincenzo Librandi, Aug 10 2016
(PARI) r=12; q=4; for(n=r, 30, print1(prod(j=1, r, (1-q^(n-j+1))/(1-q^j)), ", ")) \\ G. C. Greubel, Jun 04 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Offset changed by Vincenzo Librandi, Aug 10 2016
STATUS
approved