Number of permutations of length n that avoid the patterns 4123, 4231, and 4312.

A257562

Number of permutations of length n that avoid the patterns 4123, 4231, and 4312.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =79a(6) =310a(7) =1251a(8) =5150a(9) =21517a(10) =90921a(11) =387595a(12) =1663936a(13) =7183750a(14) =31158310a(15) =135661904a(16) =592558096a(17) =2595232344a(18) =11392504426a(19) =50109205789a(20) =220777103354a(21) =974162444028

External references