Can't assume every entry in a table is a sequence

* lisp/ob-R.el (org-babel-R-assign-elisp): Can't assume every entry in
  a table is a sequence.

lisp/ob-R.el

@@ -167,8 +167,10 @@ This function is called by `org-babel-execute-src-block'."
 (defun org-babel-R-assign-elisp (name value colnames-p rownames-p)
   "Construct R code assigning the elisp VALUE to a variable named NAME."
   (if (listp value)
-      (let ((max (apply #'max (mapcar #'length value)))
-	    (min (apply #'min (mapcar #'length value)))
+      (let ((max (apply #'max (mapcar #'length (org-remove-if-not
+						#'sequencep value))))
+	    (min (apply #'min (mapcar #'length (org-remove-if-not
+						#'sequencep value))))
 	    (transition-file (org-babel-temp-file "R-import-")))
         ;; ensure VALUE has an orgtbl structure (depth of at least 2)
         (unless (listp (car value)) (setq value (list value)))