Number of permutations of [n] avoiding {3412, 4132, 1324}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =73a(6) =239a(7) =740a(8) =2194a(9) =6298a(10) =17653a(11) =48621a(12) =132199a(13) =356040a(14) =952154a(15) =2533014a(16) =6712221a(17) =17734489a(18) =46753127a(19) =123048884a(20) =323441770a(21) =849373210a(22) =2228871757a(23) =5845630221a(24) =15324795631a(25) =40162310568a(26) =105229244354a(27) =275659639590a(28) =722018109189