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A336719
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Largest odd prime p for which the order of 2 mod p is at most n.
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3
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3, 7, 7, 31, 31, 127, 127, 127, 127, 127, 127, 8191, 8191, 8191, 8191, 131071, 131071, 524287, 524287, 524287, 524287, 524287, 524287, 524287, 524287, 524287, 524287, 524287, 524287, 2147483647, 2147483647, 2147483647, 2147483647, 2147483647, 2147483647
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OFFSET
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2,1
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COMMENTS
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a(1) is undefined.
Changing "at most n" to "equal to n" in the definition gives A097406.
The first term that is not a Mersenne prime (A000668) is 4432676798593.
For a version without duplicates, see A336720. For a list of all n where a(n) increases, see A336721.
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LINKS
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PROG
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(PARI) re=0; for(n=2, +oo, p=vecmax(factor(2^n-1)[, 1]); p>re&&re=p; print1(re, ", "))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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