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One-third of the even-indexed entries of A259056.
1

%I #7 Dec 10 2016 22:37:33

%S -1,20,-560,20160,-887040,46126080,-2767564800,188194406400,

%T -14302774886400,1201433090457600,-110531844322099200,

%U 11053184432209920000,-1193743918678671360000,138474294566725877760000,-17170812526274008842240000

%N One-third of the even-indexed entries of A259056.

%C It is conjectured that this is an integer sequence.

%C For the odd-indexed entries of A259056 see

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

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

%Y Cf. A034976, A259056.

%K sign,easy

%O 1,2

%A _Wolfdieter Lang_, Jul 07 2015