OFFSET
7,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 7..200
FORMULA
G.f.: x^7/((1-x)*(1-2*x)*(1-4*x)*(1-8*x)*(1-16*x)*(1-32*x)*(1-64*x)*(1-128*x)). - Vincenzo Librandi, Aug 07 2016
a(n) = Product_{i=1..7} (2^(n-i+1)-1)/(2^i-1), by definition. - Vincenzo Librandi, Aug 02 2016
MATHEMATICA
Table[QBinomial[n, 7, 2], {n, 7, 24}] (* Vincenzo Librandi, Aug 02 2016 *)
PROG
(Sage) [gaussian_binomial(n, 7, 2) for n in range(7, 20)] # Zerinvary Lajos, May 25 2009
(Magma) r:=7; q:=2; [&*[(1-q^(n-i+1))/(1-q^i): i in [1..r]]: n in [r..20]]; // Vincenzo Librandi, Aug 02 2016
(PARI) r=7; q=2; for(n=r, 30, print1(prod(j=1, r, (1-q^(n-j+1))/(1-q^j)), ", ")) \\ G. C. Greubel, May 30 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Jun 14 1998
EXTENSIONS
Changed offset by Vincenzo Librandi, Aug 02 2016
STATUS
approved