Number of permutations of up to n kinds of objects, where each kind of object can occur at most two times.
A003011
Number of permutations of up to n kinds of objects, where each kind of object can occur at most two times.
Terms
- a(0) =1a(1) =3a(2) =19a(3) =271a(4) =7365a(5) =326011a(6) =21295783a(7) =1924223799a(8) =229714292041
External references
- oeis: A003011