Total number of permutations p of [n] such that |p(i+3) - p(i)| is not equal to 3 for 1 <= i <= n-3.
A117574
Total number of permutations p of [n] such that |p(i+3) - p(i)| is not equal to 3 for 1 <= i <= n-3.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =20a(5) =80a(6) =384a(7) =2240a(8) =15424a(9) =123456a(10) =1110928a(11) =11287232a(12) =127016304a(13) =1565107248a(14) =20935873872a(15) =301974271248
External references
- oeis: A117574