设 2n -1=10k+7 和 2n -1=10k+9,若 f(n) 能被 2n -1 整除,则 2n -1 一定是素数。
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反例:
{57,77,129,417,437,489,849,957,1137,1497,1569,1857,1929,2217,2577,2649,3369,3477,4377,4449,4737,4757,5097,5169,6249,6537,6557,6609,7617,7917,7977,8049,8409,9057,9489,9777} |