Number of permutations of 3 indistinguishable copies of 1,...,n such that there are exactly j numbers between the first and the third copy of j and floor(j/2) numbers between the first and the second or between the second and the third copy of j.
A320392
Number of permutations of 3 indistinguishable copies of 1,...,n such that there are exactly j numbers between the first and the third copy of j and floor(j/2) numbers between the first and the second or between the second and the third copy of j.
Terms
- a(0) =1a(1) =1a(2) =0a(3) =0a(4) =4a(5) =4a(6) =10a(7) =24a(8) =252a(9) =410a(10) =1998a(11) =7798a(12) =65188a(13) =280582a(14) =2281108a(15) =10585748a(16) =110903088
External references
- oeis: A320392