Number of permutations of length n which avoid the patterns 3421, 4123, 4213.

A116743

Number of permutations of length n which avoid the patterns 3421, 4123, 4213.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =21a(4) =75a(5) =267a(6) =950a(7) =3384a(8) =12065a(9) =43034a(10) =153524a(11) =547744a(12) =1954328a(13) =6973114a(14) =24880601a(15) =88776363a(16) =316763410a(17) =1130246720a(18) =4032847433a(19) =14389658085a(20) =51343944371a(21) =183201075822a(22) =653682454214

External references