A144546 A bisection of A028666.

12, 11612160, 794088208701849600, 3575164027575627746190393606144000, 1055182047088717407398960909148529544369642384916480000, 20410164807073092317242309800149338693366138889849970301267088483593224192000000, 25872955740757748502626229629361173659982454517929458713719920139287952355803151825297413315474342543360000000

Offset: 0

Author

N. J. A. Sloane, Dec 30 2008

Keywords

• nonn

Crossrefs

Cf. A028666, A100221, A144547.

Programs

Mathematica

a[n_] := 4^(2*n+1) * Product[4^(2*n+1) - 4^k, {k, 0, 2*n}]; Array[a, 7, 0] (* Amiram Eldar, Jul 14 2025 *)

PARI

a(n) = 4^(2*n+1) * prod(k = 0, 2*n, 4^(2*n+1) - 4^k); \\ Amiram Eldar, Jul 14 2025

Formula

From Amiram Eldar, Jul 14 2025: (Start)

a(n) = A028666(2*n+1).

a(n) ~ c * 16^(2*n^2+3*n+1), where c = A100221. (End)

Extensions

a(0) = 1 removed by Amiram Eldar, Jul 14 2025