The number of 3-permutations that avoid the patterns 132 and 213.

Terms

a(0) =1a(1) =4a(2) =12a(3) =28a(4) =58a(5) =114a(6) =220a(7) =424a(8) =822a(9) =1606a(10) =3160a(11) =6252a(12) =12418a(13) =24730a(14) =49332a(15) =98512a(16) =196846a(17) =393486a(18) =786736a(19) =1573204a(20) =3146106a(21) =6291874a(22) =12583372a(23) =25166328a(24) =50332198a(25) =100663894a(26) =201327240a(27) =402653884a(28) =805307122a(29) =1610613546