Fourth differences of A129983.

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =20a(5) =44a(6) =96a(7) =209a(8) =456a(9) =999a(10) =2198a(11) =4854a(12) =10752a(13) =23877a(14) =53142a(15) =118517a(16) =264816a(17) =592744a(18) =1328880a(19) =2983565a(20) =6707396a(21) =15096727a(22) =34014866a(23) =76712042a(24) =173150400a(25) =391119273a(26) =884066890a(27) =1999489733a(28) =4524624820a(29) =10243526452