Number of distinct row/column permutations of Ferrers diagrams of integer partitions of n.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =15a(5) =39a(6) =108a(7) =290a(8) =781a(9) =2050a(10) =5434a(11) =14210a(12) =37150a(13) =96347a(14) =248250a(15) =636278a(16) =1620721a(17) =4108340a(18) =10361338a(19) =26016060a(20) =65019655a(21) =161831393a(22) =401090324a(23) =990229108a(24) =2435316984a(25) =5967684036a(26) =14572351628a(27) =35464928382a(28) =86033632280a(29) =208062026930