Number of permutations of [n] with exactly 2 descents which avoid the pattern 1324.

Terms

a(0) =0a(1) =0a(2) =1a(3) =11a(4) =55a(5) =190a(6) =526a(7) =1254a(8) =2682a(9) =5280a(10) =9735a(11) =17017a(12) =28457a(13) =45838a(14) =71500a(15) =108460a(16) =160548a(17) =232560a(18) =330429a(19) =461415a(20) =634315a(21) =859694a(22) =1150138a(23) =1520530a(24) =1988350a(25) =2574000a(26) =3301155a(27) =4197141a(28) =5293341a(29) =6625630