Number of ways n people in a line can each choose two others both on the same side of them.
A323425
Number of ways n people in a line can each choose two others both on the same side of them.
Terms
- a(0) =1a(1) =0a(2) =0a(3) =0a(4) =9a(5) =648a(6) =57600a(7) =6615000a(8) =972504225a(9) =179499220992
External references
- oeis: A323425