A203479 a(n) = Product_{1 <= i < j <= n} (2^i + 2^j - 2).

1, 4, 320, 2027520, 3855986196480, 8359491805553413324800, 79457890145647634305213865656320000, 12897878211365028383150895090566532213003150950400000, 140613650417826346093374124598539442743630963394643403845144815232614400000

Offset

1,2

Comments

Each term divides its successor, as in A203480.

Links

G. C. Greubel, Table of n, a(n) for n = 1..21

Maple

a:= n-> mul(mul(2^i+2^j-2, i=1..j-1), j=2..n):
seq(a(n), n=1..12);  # Alois P. Heinz, Jul 23 2017

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}]               (* A203479 *)
Table[v[n+1]/v[n], {n, z-1}]      (* A203480 *)
Table[v[n+1]/(4*v[n]), {n, z-1}]  (* A203481 *)
(* Second program *)
Table[Product[2^j +2^k -2, {j, n}, {k, j-1}], {n, 15}] (* G. C. Greubel, Aug 28 2023 *)

Prog

(Magma) [(&*[(&*[2^j+2^k-2: k in [1..j]])/(2^(j+1)-2): j in [1..n]]): n in [1..15]]; // G. C. Greubel, Aug 28 2023
(SageMath) [product(product(2^j+2^k-2 for k in range(1, j)) for j in range(1, n+1)) for n in range(1, 16)] # G. C. Greubel, Aug 28 2023

Crossrefs

Cf. A000225, A093883, A203305, A203480, A203481.

Sequence in context: A027512 A153220 A227673 * A034226 A186163 A159492

Adjacent sequences: A203476 A203477 A203478 * A203480 A203481 A203482

Keyword

nonn

Author

Clark Kimberling, Jan 02 2012

Extensions

Name edited by Alois P. Heinz, Jul 23 2017

Status

approved