(main): Handle the case in which seq is given no args.

src/seq.c

@@ -140,6 +140,12 @@ main (int argc, char **argv)
   }
 #endif
 
+  if (argc == 1)
+    {
+      error (0, 0, _("too few arguments"));
+      usage (1);
+    }
+
   /* We have to handle negative numbers in the command line but this
      conflicts with the command line arguments.  So explicitly check first
      whether the next argument looks like a negative number.  */