Number of 4-separable partitions of n; see Comments.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =2a(6) =2a(7) =2a(8) =3a(9) =5a(10) =6a(11) =7a(12) =8a(13) =11a(14) =13a(15) =17a(16) =19a(17) =23a(18) =27a(19) =34a(20) =40a(21) =47a(22) =55a(23) =66a(24) =77a(25) =92a(26) =106a(27) =125a(28) =145a(29) =171