Number of permutations of 2 copies of 1..n with no element e[i>=2]<e[1+floor((i-2)/5)] (5-way heap).
A178015
Number of permutations of 2 copies of 1..n with no element e[i>=2]<e[1+floor((i-2)/5)] (5-way heap).
Terms
- a(0) =1a(1) =3a(2) =30a(3) =246a(4) =5400a(5) =134550a(6) =5380020a(7) =379593000a(8) =18277228800
External references
- oeis: A178015