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%I #26 May 08 2021 22:58:20
%S 3,5,7,13,19,23,31,37,43,53,61,73,79,83,89,103,113,113,131,139,139,
%T 157,163,173,193,199,199,211,211,223,251,257,271,277,293,293,313,317,
%U 331,337,353,359,379,383,389,397,421,443,449,457,463,467,479,499,509,523
%N a(n) = largest prime < 2*prime(n).
%C Also, smallest member of the first pair of consecutive primes such that between them is a composite number divisible by the n-th prime. - _Amarnath Murthy_, Sep 25 2002
%C Except for its initial term, A006992 is a subsequence based on iteration of n -> A151799(2n). The range of this sequence is a subset of A065091. - _M. F. Hasler_, May 08 2016
%H Zak Seidov, <a href="/A059788/b059788.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = A007917(A100484(n)). - _R. J. Mathar_, May 08 2016
%e n=18: p(18)=61, so a(18) is the largest prime below 2*61=122, which is 113.
%p with(numtheory):
%p A059788 := proc(n)
%p prevprime(2*ithprime(n)) ;
%p end proc:
%p seq(A059788(n),n=1..50) ; # _R. J. Mathar_, May 08 2016
%t a[n_] := Prime[PrimePi[2Prime[n]]]
%t NextPrime[2*Prime[Range[100]], -1] (* _Zak Seidov_, May 08 2016 *)
%o (PARI) a(n) = precprime(2*prime(n)); \\ _Michel Marcus_, May 08 2016
%Y Cf. A005382, A005383, A005384, A005385, A055496, A006992, A052248.
%K nonn
%O 1,1
%A _Labos Elemer_, Feb 22 2001
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