Number of permutations of [n] avoiding {1324, 2314, 2431}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =76a(6) =271a(7) =938a(8) =3146a(9) =10252a(10) =32583a(11) =101368a(12) =309697a(13) =931708a(14) =2766374a(15) =8121630a(16) =23612985a(17) =68076148a(18) =194824915a(19) =553979438a(20) =1566301826a(21) =4406286736a(22) =12340335627a(23) =34422720496a(24) =95676632581a(25) =265071811456a(26) =732238423646