![\"\"](\"https://assets.leetcode.com/uploads/2020/08/18/chess.jpg\")
The chess knight has a unique movement, it may move two squares vertically and one square horizontally, or two squares horizontally and one square vertically (with both forming the shape of an L). The possible movements of chess knight are shown in this diagaram:
\n\nA chess knight can move as indicated in the chess diagram below:
\n\nWe have a chess knight and a phone pad as shown below, the knight can only stand on a numeric cell (i.e. blue cell).
\n![\"\"](\"https://assets.leetcode.com/uploads/2020/08/18/phone.jpg\")
\nGiven an integer n, return how many distinct phone numbers of length n we can dial.
You are allowed to place the knight on any numeric cell initially and then you should perform n - 1 jumps to dial a number of length n. All jumps should be valid knight jumps.
As the answer may be very large, return the answer modulo 109 + 7.
\n
Example 1:
\n\n\nInput: n = 1\nOutput: 10\nExplanation: We need to dial a number of length 1, so placing the knight over any numeric cell of the 10 cells is sufficient.\n\n\n
Example 2:
\n\n\nInput: n = 2\nOutput: 20\nExplanation: All the valid number we can dial are [04, 06, 16, 18, 27, 29, 34, 38, 40, 43, 49, 60, 61, 67, 72, 76, 81, 83, 92, 94]\n\n\n
Example 3:
\n\n\nInput: n = 3131\nOutput: 136006598\nExplanation: Please take care of the mod.\n\n\n
\n
Constraints:
\n\n1 <= n <= 5000象棋骑士有一个独特的移动方式，它可以垂直移动两个方格，水平移动一个方格，或者水平移动两个方格，垂直移动一个方格(两者都形成一个 L 的形状)。
\n\n象棋骑士可能的移动方式如下图所示:
\n\n
我们有一个象棋骑士和一个电话垫，如下所示，骑士只能站在一个数字单元格上(即蓝色单元格)。
\n\n
给定一个整数 n，返回我们可以拨多少个长度为 n 的不同电话号码。
\n\n你可以将骑士放置在任何数字单元格上，然后你应该执行 n - 1 次移动来获得长度为 n 的号码。所有的跳跃应该是有效的骑士跳跃。
\n\n因为答案可能很大，所以输出答案模 109 + 7.
\n\n
示例 1：
\n\n\n输入：n = 1\n输出：10\n解释：我们需要拨一个长度为1的数字，所以把骑士放在10个单元格中的任何一个数字单元格上都能满足条件。\n\n\n
示例 2：
\n\n\n输入：n = 2\n输出：20\n解释：我们可以拨打的所有有效号码为[04, 06, 16, 18, 27, 29, 34, 38, 40, 43, 49, 60, 61, 67, 72, 76, 81, 83, 92, 94]\n\n\n
示例 3：
\n\n\n输入：n = 3131\n输出：136006598\n解释：注意取模\n\n\n
\n\n
提示：
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