cp's OEIS Frontend

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.

%I A217671 #20 Oct 17 2012 13:53:01
%S A217671 3,3,3,73,523,6581,10753,43103,43103,43103,55457,55457,28751773,
%T A217671 278689963,278689963,784284211,4440915607,8340839629,30651695947,
%U A217671 50246427391,50246427391
%N 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.
%C A217671 If a(N) = 0, then a(n) = 0 for n > N. Conjecture 39 in the Shevelev link says that a(n) > 0.
%H A217671 V. Shevelev, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL15/Shevelev/shevelev19.html">Ramanujan and Labos primes, their generalizations, and classifications of primes</a>, J. Integer Seq. 15 (2012) Article 12.5.4
%Y A217671 Cf. A166251, A182405, A182523, A182426.
%K A217671 nonn
%O A217671 2,1
%A A217671 _Vladimir Shevelev_, Oct 10 2012
%E A217671 a(14) from _John W. Layman_ and _Hans Havermann_
%E A217671 a(15)-a(17) from _Carlos Rivera_ and _Hans Havermann_
%E A217671 a(18)-a(20) from _Hans Havermann_
%E A217671 a(21)-a(22) from _Donovan Johnson_, Oct 17 2012