Number of permutations of length n which are contained in a pin sequence.
A138619
Number of permutations of length n which are contained in a pin sequence.
Terms
- a(0) =1a(1) =2a(2) =6a(3) =24a(4) =120a(5) =664a(6) =3596a(7) =19004a(8) =99596a(9) =521420a(10) =2731292a(11) =14313052a(12) =75016940a(13) =393181820a(14) =2060736460a(15) =10800601788a(16) =56607287052a(17) =296685718140
External references
- oeis: A138619