First differences of A000043.

Terms

a(0) =1a(1) =2a(2) =2a(3) =6a(4) =4a(5) =2a(6) =12a(7) =30a(8) =28a(9) =18a(10) =20a(11) =394a(12) =86a(13) =672a(14) =924a(15) =78a(16) =936a(17) =1036a(18) =170a(19) =5266a(20) =252a(21) =1272a(22) =8724a(23) =1764a(24) =1508a(25) =21288a(26) =41746a(27) =24260a(28) =21546a(29) =84042