First differences of A052980.

Terms

a(0) =0a(1) =1a(2) =3a(3) =6a(4) =13a(5) =29a(6) =64a(7) =141a(8) =311a(9) =686a(10) =1513a(11) =3337a(12) =7360a(13) =16233a(14) =35803a(15) =78966a(16) =174165a(17) =384133a(18) =847232a(19) =1868629a(20) =4121391a(21) =9090014a(22) =20048657a(23) =44218705a(24) =97527424a(25) =215103505a(26) =474425715a(27) =1046378854a(28) =2307861213