Number of ordered pairs (p,q) of permutations of [n] with equal up-down signatures and p(1)=1 if n>0.
A262233
Number of ordered pairs (p,q) of permutations of [n] with equal up-down signatures and p(1)=1 if n>0.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =3a(4) =20a(5) =220a(6) =3648a(7) =84616a(8) =2617696a(9) =104112576a(10) =5176135040a(11) =314525766016
External references
- oeis: A262233