A259057 One-third of the even-indexed entries of A259056.

-1, 20, -560, 20160, -887040, 46126080, -2767564800, 188194406400, -14302774886400, 1201433090457600, -110531844322099200, 11053184432209920000, -1193743918678671360000, 138474294566725877760000, -17170812526274008842240000

Offset: 1

Author

Wolfdieter Lang, Jul 07 2015

Keywords

• sign
• easy

Comments

It is conjectured that this is an integer sequence.

For the odd-indexed entries of A259056 see

(-1)^(n-1)*A034976(n), n >= 1.

Crossrefs

Cf. A034976, A259056.

Formula

a(n) = A259056(2*n)/3, n >= 1.