Number of permutations of 3 copies of 1..n with no element e[i>=2]<e[1+floor((i-2)/2)] (2-way heap).
A178017
Number of permutations of 3 copies of 1..n with no element e[i>=2]<e[1+floor((i-2)/2)] (2-way heap).
Terms
- a(0) =1a(1) =4a(2) =38a(3) =820a(4) =42928a(5) =2352068a(6) =273609756a(7) =39956342600
External references
- oeis: A178017