Number of sortable normal multiset partitions of weight n.

Terms

a(0) =1a(1) =1a(2) =4a(3) =15a(4) =59a(5) =230a(6) =901a(7) =3522a(8) =13773a(9) =53847a(10) =210527a(11) =823087a(12) =3218002a(13) =12581319a(14) =49188823a(15) =192312112a(16) =751877137a(17) =2939592383a(18) =11492839729a(19) =44933224559a(20) =175674134309a(21) =686828104551