Number of permutations of [n] with a unique pair of orthogonal (diagonal, antidiagonal) X-rays.
A290279
Number of permutations of [n] with a unique pair of orthogonal (diagonal, antidiagonal) X-rays.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =22a(5) =110a(6) =628a(7) =4396a(8) =34496a(9) =309230a(10) =3069808
External references
- oeis: A290279