trac #16662: A comment about n<N-2

sagemath · Aug 15, 2014 · a9b594f · a9b594f
1 parent 7e0480e
commit a9b594f
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/src/sage/combinat/designs/orthogonal_arrays_recursive.py b/src/sage/combinat/designs/orthogonal_arrays_recursive.py
@@ -981,7 +981,8 @@ def find_thwart_lemma_3_5(k,N):
     k = int(k)
     N = int(N)
 
-    for n in prime_powers(k+2,N-2): # There must exist a OA(k+3,n)
+    for n in prime_powers(k+2,N-2): # There must exist a OA(k+3,n) thus n>=k+2
+                                    # At least 3 columns are nonempty thus n<N-2
 
         # we look for (m,n,a,b,c,d) with N = mn + a + b + c (+d) and
         # 0 <= a,b,c,d <= n