A335010 a(n) = Product_{k=1..n} (2^k - 1)^k.

1, 9, 3087, 156279375, 4474145825060625, 279739266376566114746420625, 149066302192479440045478394157489352699375, 2665022756273454714861436593121414601862237540654765380859375

Offset: 1

Author

Vaclav Kotesovec, May 19 2020

Keywords

• nonn

Crossrefs

Cf. A002884, A005329, A048651, A185995, A203303, A335011.

Programs

Mathematica

Table[Product[(2^k - 1)^k, {k, 1, n}], {n, 1, 10}]

PARI

a(n) = prod(k=1, n, (2^k-1)^k); \\ Michel Marcus, May 19 2020

Formula

a(n) ~ c * 2^(n*(n+1)*(2*n+1)/6), where c = A335011 = Product_{k>=1} (1 - 1/2^k)^k.