A203477 a(n) = Product_{0 <= i < j <= n-1} (2^i + 2^j).

1, 3, 90, 97200, 14276736000, 1107198567383040000, 178601637561927097909248000000, 237856509917156074017606774172522905600000000, 10420480393274493153643458442091600404477248333907230720000000000

Offset

1,2

Comments

Each term divides its successor, as in A203478.

Links

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

Maple

a:= n-> mul(mul(2^i+2^j, i=0..j-1), j=1..n-1):
seq(a(n), n=1..10);  # Alois P. Heinz, Jul 23 2017

Mathematica

(* First program *)
f[j_]:= 2^(j-1); z = 13;
v[n_]:= Product[Product[f[k] + f[j], {j, k-1}], {k, 2, n}]
Table[v[n], {n, z}]                       (* A203477 *)
Table[v[n+1]/v[n], {n, z-1}]              (* A203478 *)
Table[v[n]*v[n+2]/(2*v[n+1]^2), {n, 22}]  (* A164051 *)
(* Second program *)
Table[Product[(2^j^2)*QPochhammer[-1/2^j, 2, j], {j, 0, n-1}], {n, 20}] (* G. C. Greubel, Aug 28 2023 *)

Prog

(PARI) a(n)=prod(i=0, n-2, prod(j=i+1, n-1, 2^i+2^j)) \\ Charles R Greathouse IV, Feb 16 2021
(Magma) [(&*[(&*[2^j + 2^k: k in [0..j]])/2^(j+1): j in [0..n-1]]): n in [1..20]]; // G. C. Greubel, Aug 28 2023
(SageMath) [product(product(2^j + 2^k for k in range(j)) for j in range(n)) for n in range(1, 21)] # G. C. Greubel, Aug 28 2023

Crossrefs

Cf. A000079, A093883, A164051, A203305, A203478.

Sequence in context: A132556 A053996 A218143 * A339580 A374392 A115704

Adjacent sequences: A203474 A203475 A203476 * A203478 A203479 A203480

Keyword

nonn,easy

Author

Clark Kimberling, Jan 02 2012

Extensions

Name edited by Alois P. Heinz, Jul 23 2017

Status

approved