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A321058 Indices of records in A067849. 0
1, 2, 44, 561329, 9549959, 42932384, 13044904289 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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)

LINKS

Table of n, a(n) for n=1..7.

EXAMPLE

2 is a term because A067849(2) = 4 > A067849(1) = 2.

44 is a term because A067849(44) = 6 > A067869(2) = 4.

PROG

(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

CROSSREFS

Cf. A067849, A005602, A057331, A063378.

Sequence in context: A291808 A161745 A048566 * A342827 A264438 A241762

Adjacent sequences:  A321055 A321056 A321057 * A321059 A321060 A321061

KEYWORD

nonn,more

AUTHOR

Torlach Rush, Oct 26 2018

EXTENSIONS

a(7) from Amiram Eldar, Nov 10 2018

STATUS

approved

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Last modified May 20 11:52 EDT 2022. Contains 353871 sequences. (Running on oeis4.)