Number of 321-hexagon-avoiding permutations in S_n, i.e., permutations of 1..n with no submatrix equivalent to 321, 56781234, 46781235, 56718234 or 46718235.

A058094

Number of 321-hexagon-avoiding permutations in S_n, i.e., permutations of 1..n with no submatrix equivalent to 321, 56781234, 46781235, 56718234 or 46718235.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =5a(4) =14a(5) =42a(6) =132a(7) =429a(8) =1426a(9) =4806a(10) =16329a(11) =55740a(12) =190787a(13) =654044a(14) =2244153a(15) =7704047a(16) =26455216a(17) =90860572a(18) =312090478a(19) =1072034764a(20) =3682565575a(21) =12650266243a(22) =43456340025a(23) =149282561256a(24) =512821712570

External references