a(n) is the hafnian of the 2n X 2n symmetric Pascal matrix defined by M[i, j] = A007318(i + j - 2, i - 1).

A357419

a(n) is the hafnian of the 2n X 2n symmetric Pascal matrix defined by M[i, j] = A007318(i + j - 2, i - 1).

Terms

    a(0) =1a(1) =1a(2) =17a(3) =4929a(4) =23872137

External references