{"trustable":false,"prependHtml":"\u003cscript\u003e window.katexOptions \u003d { disable: true }; \u003c/script\u003e\n\u003cscript type\u003d\"text/x-mathjax-config\"\u003e\n MathJax.Hub.Config({\n tex2jax: {\n inlineMath: [[\u0027$$$\u0027,\u0027$$$\u0027], [\u0027$\u0027,\u0027$\u0027]],\n displayMath: [[\u0027$$$$$$\u0027,\u0027$$$$$$\u0027], [\u0027$$\u0027,\u0027$$\u0027]]\n }\n });\n\u003c/script\u003e\n\u003cscript async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\" type\u003d\"text/javascript\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"HTML","content":"\u003cdiv\u003e \n \u003cspan\u003e\u003cspan\u003e符号三角形的\u003c/span\u003e\u003c/span\u003e \n \u003cspan\u003e\u003cspan\u003e第1行有n个由“\u003c/span\u003e\u003c/span\u003e+ \n \u003cspan\u003e\u003cspan\u003e”和”-“组成的符号\u003c/span\u003e\u003c/span\u003e \n \u003cspan\u003e\u003cspan\u003e,以后每行符号比上行少1个,2个同号下面是”\u003c/span\u003e\u003c/span\u003e+ \n \u003cspan\u003e\u003cspan\u003e“,2个异\u003c/span\u003e\u003c/span\u003e \n \u003cspan\u003e\u003cspan\u003e号下面是”-“\u003c/span\u003e\u003c/span\u003e \n \u003cspan\u003e\u003cspan\u003e。计算有多少个不同的符号三角形,使其所含”\u003c/span\u003e\u003c/span\u003e+“ 和”-“ \n \u003cspan\u003e\u003cspan\u003e的个数相同\u003c/span\u003e\u003c/span\u003e 。 n\u003d \n \u003cspan\u003e\u003cspan\u003e7时的1个符号三角形如下\u003c/span\u003e\u003c/span\u003e:\n \u003cbr\u003e \n \u003cdiv\u003e\n + + - + - + +\n \u003c/div\u003e \n \u003cdiv\u003e\n \u0026nbsp;+ - - - - +\n \u003c/div\u003e \n \u003cdiv\u003e\n \u0026nbsp; - + + + -\n \u003c/div\u003e \n \u003cdiv\u003e\n \u0026nbsp; \u0026nbsp;- + + -\n \u003c/div\u003e \n \u003cdiv\u003e\n \u0026nbsp; \u0026nbsp; - + -\n \u003c/div\u003e \n \u003cdiv\u003e\n \u0026nbsp; \u0026nbsp; \u0026nbsp;- -\n \u003c/div\u003e \n \u003cdiv\u003e\n \u0026nbsp; \u0026nbsp; \u0026nbsp; +\n \u003c/div\u003e \n \u003cdiv\u003e\n \u0026nbsp;\n \u003c/div\u003e \n\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cdiv\u003e \n \u003cspan\u003e\u003cspan\u003e每行1个正整数n\u003c/span\u003e\u003c/span\u003e \u0026lt;\u003d24,n\u003d \n \u003cspan\u003e\u003cspan\u003e0退出\u003c/span\u003e\u003c/span\u003e.\n\u003c/div\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cdiv\u003e \n \u003cspan\u003e\u003cspan\u003en和符号三角形的个数\u003c/span\u003e\u003c/span\u003e.\n\u003c/div\u003e"}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cdiv\u003e \n \u003cdiv\u003e\n \u0026nbsp;\n \u003c/div\u003e \n \u003cdiv\u003e \n \u003cdiv\u003e\n 15\n \u003cbr\u003e 16\n \u003cbr\u003e 19\n \u003cbr\u003e 20\n \u003cbr\u003e 0\u0026nbsp;\n \u003c/div\u003e \n \u003c/div\u003e \n\u003c/div\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cdiv\u003e \n \u003cdiv\u003e\n \u0026nbsp;\n \u003c/div\u003e \n \u003cdiv\u003e \n \u003cdiv\u003e\n 15 1896\n \u003cbr\u003e 16 5160\n \u003cbr\u003e 19 32757\n \u003cbr\u003e 20 59984\u0026nbsp;\n \u003c/div\u003e \n \u003c/div\u003e \n\u003c/div\u003e"}}]}