Number of permutations of [n] with exactly 3 descents which avoid the pattern 1324.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =26a(5) =229a(6) =1246a(7) =5086a(8) =17084a(9) =49768a(10) =129958a(11) =311051a(12) =693290a(13) =1455909a(14) =2906436a(15) =5554172a(16) =10217000a(17) =18173272a(18) =31373636a(19) =52731365a(20) =86514106a(21) =138865053a(22) =218487442a(23) =337533050a(24) =512743140a(25) =766899120a(26) =1130650170a(27) =1644796335a(28) =2363118186a(29) =3355858221