Number of permutations of length n containing exactly once 132 and 213, likewise for pattern pair (231,312).

A089264

Number of permutations of length n containing exactly once 132 and 213, likewise for pattern pair (231,312).

Terms

    a(0) =3a(1) =6a(2) =17a(3) =42a(4) =102a(5) =242a(6) =564a(7) =1296a(8) =2944a(9) =6624a(10) =14784a(11) =32768a(12) =72192a(13) =158208a(14) =345088a(15) =749568a(16) =1622016a(17) =3497984a(18) =7520256a(19) =16121856a(20) =34471936a(21) =73531392a(22) =156499968a(23) =332398592a(24) =704643072a(25) =1491075072a(26) =3149922304a(27) =6643777536a(28) =13992198144

External references