%I #22 Jun 14 2019 00:11:46
%S 2,2,3,3,5,5,7,7,11,11,13,13,17,17,19,19,23,23,29,29,31,31,37,37,41,
%T 41,43,43,47,47,53,53,59,59,61,61,67,67,71,71,73,73,79,79,83,83,89,89,
%U 97,97,101,101,103,103,107,107,109,109,113,113,127,127,131,131
%N Primes repeated.
%F a(n) = A000040(ceiling(n/2)). - _Jon Perry_, Oct 29 2014
%t With[{prs=Prime[Range[40]]},Riffle[prs,prs]] (* _Harvey P. Dale_, Oct 10 2014 *)
%K easy,nonn
%O 1,1
%A _Giovanni Teofilatto_, Aug 13 2005