中文摘要：

k错线性复杂度作为密钥流序列稳定性的重要指标，对于衡量密钥流序列密码强度具有十分重要的意义，研究具有高k错线性复杂度的序列也一直是序列密码中的热点问题。该文在XWLI算法基础上，给出k错线性复杂度小于等于pn-1时pn周期二元序列的3错线性复杂度的原序列计数公式，并通过实例验证了该文理论的正确性和合理性，该文方法同样适用于研究pn 周期q元序列的计数。

英文摘要：

The k-error linear complexity have been used to measure stability of keystream sequences .It is extremely important for studying keystream strength .The studies of high k-error linear complexity have also been a hot in stream cipher .On the basis of XWLI algorithm , counting functions on 3-error linear complexity of p n-periodic binary sequences when k-error linear complexity is less than p n-1 are derived .They are also verified by computer program .The method is also applicable to research p n-periodic q sequences .