OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..21
FORMULA
a(n) = Product_{k=1..n-1} Product_{j=1..k} (2^(k+1) - 2^j).
From Vaclav Kotesovec, Feb 18 2021: (Start)
a(n) = (-1)^n * (2^(n*(n+1)*(2*n+1)/6 - 1) / QPochhammer(2,2,n)) * Product_{k=2..n} QPochhammer(1/2^k, 2, k).
a(n) ~ 2^(n*(n^2 - 1)/3) * QPochhammer(1/2)^n / A335011. (End)
a(n) = Product_{k=2..n} ( 2^(k+1)^2 * QPochhammer(2^(-k-1), 2, k+1) )/ (2^(k+1) - 1). - G. C. Greubel, Aug 30 2023
MATHEMATICA
(* First program *)
f[j_]:= 2^j - 1; z = 15;
v[n_]:= Product[Product[f[k] - f[j], {j, k-1}], {k, 2, n}]
Table[v[n], {n, z}] (* A203305 *)
Table[v[n+1]/v[n], {n, z}] (* A028365 *)
%/2 (* A203307 *)
(* Second program *)
Table[(-1)^n * 2^(n*(n+1)*(2*n+1)/6 - 1) / QPochhammer[2, 2, n] * Product[QPochhammer[1/2^k, 2, k], {k, 2, n}], {n, 10}] (* Vaclav Kotesovec, Feb 18 2021 *)
PROG
(Magma) [1] cat [(&*[(&*[2^(k+1) - 2^j: j in [1..k]]): k in [1..n-1]]): n in [2..15]]; // G. C. Greubel, Aug 30 2023
(SageMath) [product(product(2^k - 2^j for j in range(1, k)) for k in range(2, n+1)) for n in range(1, 16)] # G. C. Greubel, Aug 30 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jan 01 2012
STATUS
approved