Number of 4-line partitions of n (i.e., planar partitions of n with at most 4 lines).

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =13a(5) =23a(6) =45a(7) =78a(8) =141a(9) =239a(10) =409a(11) =674a(12) =1116a(13) =1794a(14) =2882a(15) =4544a(16) =7131a(17) =11031a(18) =16983a(19) =25844a(20) =39124a(21) =58680a(22) =87538a(23) =129578a(24) =190830a(25) =279140a(26) =406334a(27) =588026a(28) =847034a(29) =1213764