

A321487


Numbers in A121707 (n^3 > 1 divides Sum_{k=1..n1} k^n) which are not semiprimes.


3



275, 455, 475, 539, 575, 715, 775, 875, 935, 1075, 1127, 1175, 1235, 1295, 1375, 1421, 1463, 1475, 1495, 1547, 1595, 1615, 1675, 1715, 1775, 1859, 1955, 1975, 2009, 2015, 2035, 2057, 2075, 2093, 2135, 2255, 2261, 2299, 2303, 2375, 2387, 2555, 2575, 2597, 2635, 2639, 2675, 2717, 2783
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OFFSET

1,1


COMMENTS

Most terms of A121707 and its (conjectured) subsequence A267999 are semiprimes. This sequence lists the exceptions.
At first, it looked as if most terms were multiples of 5. The first exceptions are a({4, 11, 16}) = {539, 1127, 1421}. However, after the first 30 terms, almost every other term is not divisible by 5.
The first terms not in A267999 are {2057, 2873, 3689, 4015, 4991, 6137, ...}, cf. A321488.


LINKS



CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



