Number of length n permutations avoiding (123,{2},{}) and (123,{},{1}).

A249562

Number of length n permutations avoiding (123,{2},{}) and (123,{},{1}).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =5a(4) =14a(5) =43a(6) =143a(7) =509a(8) =1921a(9) =7631a(10) =31725a(11) =137412a(12) =617822a(13) =2874819a(14) =13809305a(15) =68331089a(16) =347657464a(17) =1815839759a(18) =9722708061a(19) =53301771604a(20) =298854490602

External references