a(n) = n^(2*n) - 1.A117812a(n) = n^(2*n) - 1.Terms a(0) =0a(1) =0a(2) =15a(3) =728a(4) =65535a(5) =9765624a(6) =2176782335a(7) =678223072848External referencesoeis: A117812