a(n) = (-1)^(n+1)*(3/4)*(9^n-1)*B(2*n) where B(k) denotes the k-th Bernoulli number.

A090643

a(n) = (-1)^(n+1)*(3/4)*(9^n-1)*B(2*n) where B(k) denotes the k-th Bernoulli number.

Terms

    a(0) =0a(1) =1a(2) =2a(3) =13a(4) =164a(5) =3355a(6) =100886a(7) =4185097a(8) =228970568a(9) =15972720439

External references