%I A118491
%S A118491 1,2,6,30,210,2310,30030,510510,9699690,223092870,6469693230,
%T A118491 200560490130,7420738134810,304250263527210,14299762385778870,
%U A118491 757887406446280110,44715356980330526490,2995928917682145274830
%N A118491 Product of first n Chen primes.
%C A118491 This first differs from primorials A002110 at a(14) = 14299762385778870 
               = 47*a(13) rather than 43*a(13) because 43 is the smallest prime 
               that is not a Chen prime (A102540). [From Jonathan Vos Post (jvospost3(AT)gmail.com), 
               Dec 25 2008]
%e A118491 a(0) = 1 by definition. a(1) = 2, 2 is first Chen prime, a(2) = 6 since 
               it is a product of two first Chen primes 2 and 3, ...
%p A118491 ischenprime:=proc(n); if (isprime(n) = 'true') then if (isprime(n+2) 
               = 'true' or numtheory[bigomega](n+2) = 2) then RETURN('true') else 
               RETURN('false') fi fi end: ts_chen_prim_numbers:=proc(n) local i,
               ans,tren; ans:=[1]: tren:=1: for i from 1 to n do if (ischenprime(i) 
               = 'true') then tren := i*tren: ans:=[op(ans), tren]: fi od; RETURN(ans) 
               end: ts_chen_prim_numbers(140);
%Y A118491 Cf. A002110, A109611.
%Y A118491 Cf. A102540. [From Jonathan Vos Post (jvospost3(AT)gmail.com), Dec 25 
               2008]
%Y A118491 Sequence in context: A068215 A096775 A002110 this_sequence A088257 A058694 
               A046853
%Y A118491 Adjacent sequences: A118488 A118489 A118490 this_sequence A118492 A118493 
               A118494
%K A118491 nonn
%O A118491 0,2
%A A118491 Jani Melik (jani_melik(AT)hotmail.com), May 05 2006