var fs = require('fs')
function makeNum() {
    let num = '1',
      random = Math.random();
    if (random >= 0.1 && random < 0.2) {//15概率
      num += '5';
    } else if (random >= 0.05 && random < 0.1) {//18概率
      num += '8';
    } else if (random >= 0 && random < 0.05) {//17概率
      num += '7';
    } else {//13概率
      num += '3';
    }

    let numLen9 = '';
    for (let j = 0; j < 9; j++) {
      numLen9 += Math.floor(Math.random() * 10)
    }

    // 返回一个号码
    return num + numLen9;
  }
  var str = ''
for (let i = 0; i < 3000; i++) {
    str += makeNum() + '\r\n'
    
}
fs.writeFile('./num.txt', str, function(err) {
    if(err) {
        console.log(err)
    }
})