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A321058
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Indices of records in A067849.
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0
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OFFSET
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1,2
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COMMENTS
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The corresponding record values are 2,4,6,7,8,9,10.
From David A. Corneth, Nov 10 2018: (Start)
Terms a(n) are of the form 3*k+2 for n > 1.
If 2^k - 1 is composite then a(n) is not divisible by any prime factor of 2^k-1 for n > k. So for example, gcd(a(n), 105) = 1 for n > 5. (End)
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LINKS
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Table of n, a(n) for n=1..7.
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EXAMPLE
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2 is a term because A067849(2) = 4 > A067849(1) = 2.
44 is a term because A067849(44) = 6 > A067869(2) = 4.
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PROG
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(PARI) b(n) = {my(nb = 0, newn); while (isprime(newn=2*n+1), nb++; n = newn); nb; } \\ A067849
lista(nn) = {my(mmax = -1, mm); for (n=1, nn, if ((mm=b(n)) > mmax, mmax = mm; print1(n, ", ")); ); } \\ Michel Marcus, Nov 10 2018
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CROSSREFS
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Cf. A067849, A005602, A057331, A063378.
Sequence in context: A291808 A161745 A048566 * A342827 A264438 A241762
Adjacent sequences: A321055 A321056 A321057 * A321059 A321060 A321061
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KEYWORD
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nonn,more
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AUTHOR
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Torlach Rush, Oct 26 2018
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EXTENSIONS
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a(7) from Amiram Eldar, Nov 10 2018
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STATUS
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approved
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