diff --git a/notebooks/problem0031.ipynb b/notebooks/problem0031.ipynb
index 1f5b971..a51ad1b 100644
--- a/notebooks/problem0031.ipynb
+++ b/notebooks/problem0031.ipynb
@@ -119,6 +119,15 @@
     "f(x) = 1/prod(1 - x^k for k in (1, 2, 5, 10, 20, 50, 100, 200))\n",
     "f(x).taylor(x, 0, 200).coefficient(x^200)"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "32707270",
+   "metadata": {},
+   "source": [
+    "## Relevant sequences\n",
+    "* Number of ways to make change with Euro currency (same values as this problem until $n=500$): [A057537](https://oeis.org/A057537)"
+   ]
   }
  ],
  "metadata": {