From the expansion of sinh(x) / cos(x): a(n) = odd part of A002084(n).

A002085

From the expansion of sinh(x) / cos(x): a(n) = odd part of A002084(n).

Terms

    a(0) =1a(1) =1a(2) =9a(3) =39a(4) =1141a(5) =12721a(6) =804309a(7) =17113719a(8) =1886573641a(9) =65373260641

External references