a(n) = (42^n - 1)/41.A218745a(n) = (42^n - 1)/41.Terms a(0) =0a(1) =1a(2) =43a(3) =1807a(4) =75895a(5) =3187591a(6) =133878823a(7) =5622910567a(8) =236162243815External referencesoeis: A218745