The number of planar partitions of n with adjacent parts differing by no more than 1.

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =11a(5) =19a(6) =34a(7) =53a(8) =89a(9) =141a(10) =224a(11) =346a(12) =542a(13) =815a(14) =1246a(15) =1862a(16) =2772a(17) =4085a(18) =6003a(19) =8720a(20) =12653a(21) =18190a(22) =26072a(23) =37122a(24) =52679a(25) =74298a(26) =104458a(27) =146129a(28) =203713a(29) =282779