Number of permutations of 1..n with no adjacent pair summing to n+6.
A173846
Number of permutations of 1..n with no adjacent pair summing to n+6.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =120a(6) =720a(7) =3600a(8) =30240a(9) =221760a(10) =2338560a(11) =22176000a(12) =280143360a(13) =3242695680a(14) =47638886400a(15) =649729382400
External references
- oeis: A173846