Number of permutations of length n which avoid both the patterns 3241 and 4321. Or, equivalently, avoids both 1234 and 1342.
A165543
Number of permutations of length n which avoid both the patterns 3241 and 4321. Or, equivalently, avoids both 1234 and 1342.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =22a(5) =89a(6) =380a(7) =1678a(8) =7584a(9) =34875a(10) =162560a(11) =766124a(12) =3644066a(13) =17469863a(14) =84324840a(15) =409471090a(16) =1998933556a(17) =9804748548a(18) =48298256084a(19) =238840150970
External references
- oeis: A165543