The number of permutations of n cards in which 4 will be the next hit after 2.
A018932
The number of permutations of n cards in which 4 will be the next hit after 2.
Terms
- a(0) =0a(1) =3a(2) =10a(3) =60a(4) =408a(5) =3120a(6) =26640a(7) =252000a(8) =2620800a(9) =29756160a(10) =366508800a(11) =4869849600a(12) =69455232000
External references
- oeis: A018932