Engel expansion for (positive) constant defined in A078756.

Terms

a(0) =2a(1) =4a(2) =30a(3) =63a(4) =162a(5) =629a(6) =3918a(7) =5345a(8) =8577a(9) =10902a(10) =12073a(11) =19001a(12) =28961a(13) =33387a(14) =65944a(15) =75653a(16) =105116a(17) =179007a(18) =262900a(19) =504773a(20) =844426a(21) =1120997a(22) =3272709a(23) =5732988a(24) =11239007a(25) =25703795a(26) =29618846a(27) =40805409a(28) =46574664a(29) =123045405