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A239727 Numbers n such that the least prime of the form 2nk + 1 has a value of k that is larger than the k values for all smaller n. 4
1, 4, 12, 19, 59, 92, 159, 227, 256, 514, 706, 1466, 5207, 21209, 62809, 86914, 152351, 170167, 321472, 424783, 491702, 860831, 1415551, 1581442, 2679809, 4691576, 6238447, 6630812, 17886697, 27507569, 30581429, 57868997, 108830332, 116156102, 127813579, 154641337, 1072567492, 1101795593, 3546087418, 10371779744 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

RECORDS transform of A016014.

Sequence is infinite; a terrible upper bound can be derived from Linnik's theorem together with the Chinese Remainder Theorem, giving a(n) << exp(a(n-1)^6).

LINKS

Table of n, a(n) for n=1..40.

FORMULA

A016014(a(n)) = A239746(n). - Zak Seidov, Mar 27 2014

EXAMPLE

2*4*2+1 = 17 is prime with k = 2, but 1 through 3 have k = 1.

2*12*3+1 = 73 is prime with k = 3, but k = 2 for 4, 7, 10 and k = 1 for the other n < 12.

PROG

(PARI) A016014(n)=my(k); while(!isprime(2*n*k+++1), ); k

r=0; for(n=1, 1e8, t=A016014(n); if(t>r, r=t; print1(n", ")))

CROSSREFS

Cf. A016014, A239746.

Sequence in context: A304474 A301068 A169583 * A341888 A009557 A240762

Adjacent sequences:  A239724 A239725 A239726 * A239728 A239729 A239730

KEYWORD

nonn

AUTHOR

Charles R Greathouse IV, Mar 25 2014

EXTENSIONS

a(37)-a(40) from Giovanni Resta, Mar 26 2014

STATUS

approved

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Last modified December 3 05:05 EST 2021. Contains 349445 sequences. (Running on oeis4.)