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A128681
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Numbers k such that k^3 divides 8^(k^2) + 1.
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20
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1, 3, 9, 57, 171, 1467, 13131, 27873, 32547, 97641, 249489, 261633, 784899, 1218897, 1255347, 2140353, 4971027, 8246019, 9961491, 12914001, 14913081, 15915483, 23159043, 23851593, 24738057, 29884473, 40666707, 83512353, 127938537
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OFFSET
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1,2
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COMMENTS
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3 divides a(n) for n > 1.
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LINKS
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MATHEMATICA
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Select[Range[5*10^6], Mod[ 8^(#^2)+1, #^3]==0 &] (* G. C. Greubel, Jan 18 2018 *)
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CROSSREFS
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Cf. A127263 (numbers k such that k^3 divide 2^(k^2)+1).
Cf. A128677 (least k > p such that (k*p)^3 divides (p-1)^(k*p)^2+1, where p = prime(n) > 2).
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KEYWORD
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hard,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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