Number of permutations of 1..n with no element e[i>=2]<e[1+floor((i-2)/3)] (3-way heap).
A178008
Number of permutations of 1..n with no element e[i>=2]<e[1+floor((i-2)/3)] (3-way heap).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =6a(5) =12a(6) =40a(7) =180a(8) =630a(9) =3360a(10) =22680a(11) =113400a(12) =831600a(13) =7484400a(14) =38918880a(15) =302702400a(16) =2918916000a(17) =20432412000a(18) =205837632000
External references
- oeis: A178008