Apply (1+Shift)^3 to Bell numbers.

Terms

a(0) =1a(1) =4a(2) =8a(3) =15a(4) =37a(5) =114a(6) =409a(7) =1657a(8) =7432a(9) =36401a(10) =192713a(11) =1094076a(12) =6618379a(13) =42436913a(14) =287151994a(15) =2042803419a(16) =15229360185a(17) =118645071202a(18) =963494800557