a(1) = 1, a(2) = 2; a(n+1) = 2n*a(n) - a(n-1). Symmetrically, a(n) = (a(n-1) + a(n+1))/((n-1) + (n+1)).

A093985

a(1) = 1, a(2) = 2; a(n+1) = 2n*a(n) - a(n-1). Symmetrically, a(n) = (a(n-1) + a(n+1))/((n-1) + (n+1)).

Terms

    a(0) =1a(1) =2a(2) =7a(3) =40a(4) =313a(5) =3090a(6) =36767a(7) =511648a(8) =8149601a(9) =146181170a(10) =2915473799a(11) =63994242408

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