Third differences of A129952.

Terms

a(0) =2a(1) =3a(2) =8a(3) =18a(4) =40a(5) =88a(6) =192a(7) =416a(8) =896a(9) =1920a(10) =4096a(11) =8704a(12) =18432a(13) =38912a(14) =81920a(15) =172032a(16) =360448a(17) =753664a(18) =1572864a(19) =3276800a(20) =6815744a(21) =14155776a(22) =29360128a(23) =60817408a(24) =125829120a(25) =260046848a(26) =536870912a(27) =1107296256a(28) =2281701376a(29) =4697620480