a(n) is the hafnian of the 2n X 2n symmetric matrix defined by M[i,j] = ceiling(i*j/3).

A358162

a(n) is the hafnian of the 2n X 2n symmetric matrix defined by M[i,j] = ceiling(i*j/3).

Terms

    a(0) =1a(1) =1a(2) =11a(3) =530a(4) =71196a(5) =18680148a(6) =8825763888

External references