%I A142346
%S A142346 2,11,47,73,131,151,173,181,227,239,271,307,367,379,383,461,523,643,661,
%T A142346 677,743,797,991,997,1021,1063,1091,1307,1459,1567,1637,1723,1811,1831,
%U A142346 1951,1987,1999,2027,2111,2251,2273,2297,2543,2609,2647,2699,2707,2801
%N A142346 Primes of the form (p(n)+r(n))/2, where p(n)=n-th prime and r(n)=n-th 
               nonprime.
%e A142346 If n=2, then (p(2)+r(2))/2=(3+1)/2=2=a(1).
%e A142346 If n=6, then (p(6)+r(6))/2=(13+9)/2=11=a(2).
%e A142346 If n=19, then (p(19)+r(19))/2=(67+27)/2=47=a(3).
%e A142346 If n=28, then (p(28)+r(28))/2=(107+39)/2=73=a(4).
%e A142346 If n=46, then (p(46)+r(46))/2=(199+63)/2=131=a(5), etc.
%p A142346 A141468 := proc(n) option remember ; if n = 1 then 0; else for a from 
               procname(n-1)+1 do if not isprime(a) then RETURN(a) ; fi; od: fi: 
               end: A000040 := proc(n) ithprime(n) ; end: for n from 1 to 3000 do 
               c := A000040(n)+A141468(n) ; if c mod 2 = 0 then if isprime(c/2) 
               then printf("%d,",c/2) ; fi; fi; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               Nov 03 2008]
%Y A142346 Cf. A000040, A141468.
%Y A142346 Sequence in context: A000176 A042927 A140305 this_sequence A106980 A089682 
               A050929
%Y A142346 Adjacent sequences: A142343 A142344 A142345 this_sequence A142347 A142348 
               A142349
%K A142346 nonn
%O A142346 1,1
%A A142346 Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Sep 19 2008
%E A142346 239 inserted, 367 inserted and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               Nov 03 2008