Number of freely-braided hexagon-avoiding permutations in S_n; the freely-braided hexagon-avoiding permutations are those that avoid 3421, 4231, 4312, 4321, 46718235, 46781235, 56718234 and 56781234.
A129777
Number of freely-braided hexagon-avoiding permutations in S_n; the freely-braided hexagon-avoiding permutations are those that avoid 3421, 4231, 4312, 4321, 46718235, 46781235, 56718234 and 56781234.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =20a(5) =71a(6) =260a(7) =971a(8) =3670a(9) =13968a(10) =53369a(11) =204352a(12) =783408a(13) =3005284a(14) =11533014a(15) =44267854a(16) =169935041a(17) =652385639a(18) =2504613713a(19) =9615798516a(20) =36917689075a(21) =141737959416a(22) =544175811783
External references
- oeis: A129777