n = {m} = {1}; tmp = {2}; Do[ m++; While[ContainsAny[tmp, m + n], m++ ]; tmp = Join[tmp, n + m]; AppendTo[tmp, 2 m]; AppendTo[n, m] , {99} ] Row[Take[n, 30], ","] Row[Take[n, {91, 100}], ","]