Number of planar partitions of n with exactly 3 rows.

Terms

a(0) =1a(1) =2a(2) =5a(3) =11a(4) =22a(5) =42a(6) =78a(7) =138a(8) =239a(9) =405a(10) =669a(11) =1088a(12) =1741a(13) =2744a(14) =4267a(15) =6564a(16) =9975a(17) =15019a(18) =22394a(19) =33111a(20) =48549a(21) =70678a(22) =102127a(23) =146636a(24) =209186a(25) =296697a(26) =418401a(27) =586985a(28) =819218a(29) =1137962