Eratosthenes(100) { a[1] := 0 for i := 2 to 100 do a[i] := 1 p := 2 while p2 < 100 do { j := 2p while (j < 100) do { a[j] := 0 j := j+p } repeat p := p+1 until a[p] = 1 } return(a) }