Number of permutations of length n that avoid the patterns 3412 and 2413.

A165546

Number of permutations of length n that avoid the patterns 3412 and 2413.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =6a(4) =22a(5) =90a(6) =395a(7) =1823a(8) =8741a(9) =43193a(10) =218704a(11) =1129944a(12) =5937728a(13) =31656472a(14) =170892498a(15) =932625326a(16) =5138618526a(17) =28554124650a(18) =159874462032a(19) =901243508380

External references