1 S3(1, 1); 2 for (int c0 = 2; c0 <= M; c0 += 1) { 3 S1(c0, 1); 4 for (int c1 = 2; c1 < c0; c1 += 1) 5 S2(c0, c1); 6 S4(c0, c0); 7 } 8