a(n) = Sum_{k = 1...n} k^(2^(n - k)).A323775a(n) = Sum_{k = 1...n} k^(2^(n - k)).Terms a(0) =1a(1) =3a(2) =8a(3) =30a(4) =359a(5) =72385a(6) =4338080222External referencesoeis: A323775