a(0)=0, a(n) = n*E(2n-1) for n >= 1, where E(n) = A000111(n) are the Euler (or up-down) numbers.

A024255

a(0)=0, a(n) = n*E(2n-1) for n >= 1, where E(n) = A000111(n) are the Euler (or up-down) numbers.

Terms

    a(0) =0a(1) =1a(2) =4a(3) =48a(4) =1088a(5) =39680a(6) =2122752a(7) =156577792a(8) =15230058496

External references