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In mathematics, the n-th harmonic number is the sum of the reciprocals of the first n natural numbers:
This also equals n times the inverse of the harmonic mean of these natural numbers.
Number n such that the numerator of is prime are
2, 3, 5, 8, 9, 21, 26, 41, 56, 62, 69, 79, 89, 91, 122, 127, 143, 167, 201, 230, 247, 252, 290, 349, 376, 459, 489, 492, 516, 662, 687, 714, 771, 932, 944, 1061, 1281, 1352, 1489, 1730, 1969, ... (sequence A056903 in OEIS)
Harmonic numbers were studied in antiquity and are important in various branches of number theory. They are sometimes loosely termed harmonic...