a(n) = (2*n)! * [x^(2*n)] arctan(x / sqrt(2))^2.

A356901

a(n) = (2*n)! * [x^(2*n)] arctan(x / sqrt(2))^2.

Terms

    a(0) =0a(1) =1a(2) =-4a(3) =46a(4) =-1056a(5) =40536a(6) =-2342880a(7) =190229040a(8) =-20655129600

External references