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A303791
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Carmichael numbers (A002997) that are central polygonal numbers (A002061).
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1
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OFFSET
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1,1
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COMMENTS
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Also, Carmichael numbers of the form k^2 + k + 1.
Also, Carmichael numbers of the form k^2 - k + 1.
There are no other terms below 2^64.
Carmichael numbers m such that 4m - 3 is square. - Thomas Ordowski, Apr 30 2018
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LINKS
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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STATUS
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approved
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