Second differences of A129983.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =16a(5) =33a(6) =70a(7) =151a(8) =328a(9) =714a(10) =1556a(11) =3397a(12) =7436a(13) =16329a(14) =35974a(15) =79496a(16) =176160a(17) =391341a(18) =871338a(19) =1944079a(20) =4345700a(21) =9730886a(22) =21823468a(23) =49012777a(24) =110216952a(25) =248133169a(26) =559199786a(27) =1261385676a(28) =2847638456a(29) =6433380969