Number of permutations of [n] avoiding {4231, 3412, 1234}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =71a(6) =212a(7) =554a(8) =1289a(9) =2725a(10) =5326a(11) =9758a(12) =16941a(13) =28107a(14) =44864a(15) =69266a(16) =103889a(17) =151913a(18) =217210a(19) =304438a(20) =419141a(21) =567855a(22) =758220a(23) =999098a(24) =1300697a(25) =1674701a(26) =2134406a(27) =2694862a(28) =3373021a(29) =4187891