a(n) = A136007(n)*(A136007(n)+1)/2.A152953a(n) = A136007(n)*(A136007(n)+1)/2.Terms a(0) =6a(1) =28a(2) =496a(3) =8128a(4) =33550336a(5) =8589869056a(6) =137438691328External referencesoeis: A152953