Number of planar partitions of n with trace 4.

Terms

a(0) =1a(1) =2a(2) =6a(3) =14a(4) =33a(5) =64a(6) =127a(7) =228a(8) =404a(9) =672a(10) =1100a(11) =1724a(12) =2661a(13) =3974a(14) =5849a(15) =8402a(16) =11911a(17) =16556a(18) =22751a(19) =30772a(20) =41198a(21) =54436a(22) =71283a(23) =92316a(24) =118609a(25) =150950a(26) =190753a(27) =239090a(28) =297783a(29) =368236