Number of permutations of length n which avoid the patterns 2431, 4123, 4231.

A116819

Number of permutations of length n which avoid the patterns 2431, 4123, 4231.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =21a(4) =76a(5) =274a(6) =978a(7) =3463a(8) =12201a(9) =42869a(10) =150415a(11) =527426a(12) =1848905a(13) =6480722a(14) =22715293a(15) =79617891a(16) =279063942a(17) =978133274a(18) =3428414441a(19) =12016810218a(20) =42119714480a(21) =147632440224a(22) =517461749617

External references