Number of planar partitions of n decreasing across rows.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =7a(5) =12a(6) =21a(7) =34a(8) =56a(9) =90a(10) =143a(11) =223a(12) =348a(13) =532a(14) =811a(15) =1224a(16) =1834a(17) =2725a(18) =4031a(19) =5914a(20) =8638a(21) =12540a(22) =18116a(23) =26035a(24) =37262a(25) =53070a(26) =75292a(27) =106377a(28) =149738a(29) =209980