Number of freely braided permutations of length n; the freely braided permutations are those that avoid 3421, 4231, 4312 and 4321.
A108600
Number of freely braided permutations of length n; the freely braided permutations are those that avoid 3421, 4231, 4312 and 4321.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =20a(5) =71a(6) =260a(7) =971a(8) =3674a(9) =14032a(10) =53968a(11) =208692a(12) =810492a(13) =3158760a(14) =12346628a(15) =48377494a(16) =189952216a(17) =747180999a(18) =2943648824a(19) =11612917815a(20) =45869337526a(21) =181372345723a(22) =717856746216
External references
- oeis: A108600