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A217671 a(n) is the least prime of the set of the smallest n consecutive primes a(n)=q_1(n), q_2(n),..., such that between (1/2)*q_i  and (1/2)q_(i+1), i=1,...,n-1, there exists a prime, or a(n)=0 if no such set of primes exists. 1
3, 3, 3, 73, 523, 6581, 10753, 43103, 43103, 43103, 55457, 55457, 28751773, 278689963, 278689963, 784284211, 4440915607, 8340839629, 30651695947, 50246427391, 50246427391 (list; graph; refs; listen; history; text; internal format)



If a(N) = 0, then a(n) = 0 for n > N. Conjecture 39 in the Shevelev link says that a(n) > 0.


Table of n, a(n) for n=2..22.

V. Shevelev, Ramanujan and Labos primes, their generalizations, and classifications of primes, J. Integer Seq. 15 (2012) Article 12.5.4


Cf. A166251, A182405, A182523, A182426.

Sequence in context: A340821 A091323 A174641 * A118539 A015665 A343120

Adjacent sequences:  A217668 A217669 A217670 * A217672 A217673 A217674




Vladimir Shevelev, Oct 10 2012


a(14) from John W. Layman and Hans Havermann

a(15)-a(17) from Carlos Rivera and Hans Havermann

a(18)-a(20) from Hans Havermann

a(21)-a(22) from Donovan Johnson, Oct 17 2012



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Last modified December 9 08:41 EST 2021. Contains 349627 sequences. (Running on oeis4.)