Number of permutations pi of [n] such that s(pi) avoids the patterns 132 and 321, where s is West's stack-sorting map.
A319028
Number of permutations pi of [n] such that s(pi) avoids the patterns 132 and 321, where s is West's stack-sorting map.
Terms
- a(0) =1a(1) =2a(2) =6a(3) =22a(4) =88a(5) =364a(6) =1522a(7) =6374a(8) =26640a(9) =110980a(10) =460716a(11) =1906172a(12) =7862416a(13) =32341144a(14) =132707626a(15) =543376774a(16) =2220650656a(17) =9060011284a(18) =36908739316a(19) =150159618964a(20) =610186287376
External references
- oeis: A319028