a(n) is the number of solutions of the congruence Sum_{k=1..n} x_k == n (mod 2n) where x_k are distinct elements of the set {0,1,...,2n}.

A174668

a(n) is the number of solutions of the congruence Sum_{k=1..n} x_k == n (mod 2n) where x_k are distinct elements of the set {0,1,...,2n}.

Terms

    a(0) =1a(1) =2a(2) =24a(3) =216a(4) =3120a(5) =54720a(6) =1239840a(7) =32618880a(8) =981227520a(9) =33479308800

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