A139486 a(n) = Product_{j=0..n-1} (2^j + 2).

1, 3, 12, 72, 720, 12960, 440640, 29082240, 3780691200, 975418329600, 501365021414400, 514400511971174400, 1054521049540907520000, 4321427261018639016960000, 35409774976786728104970240000, 580224572769627326728042352640000

Offset

0,2

Links

Table of n, a(n) for n=0..15.

Formula

a(n) = A139485(2^n + 1) - 1 = Sum_{j=1..2^n} A139485(j).

For n >= 1, a(n) = 2^(n-1) * 3 * A028361(n-1).

Prog

(PARI) { a(n) = prod(j=0, n-1, 2^j+2) }

Crossrefs

Cf. A139485, A028361.

Sequence in context: A052676 A054640 A377673 * A260622 A348222 A346664

Adjacent sequences: A139483 A139484 A139485 * A139487 A139488 A139489

Keyword

easy,nonn

Author

Leroy Quet, Apr 23 2008

Extensions

Edited and extended by Max Alekseyev, Oct 24 2008

Status

approved