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 A117243 Chen numbers which are also twin primes. 0
 3, 5, 7, 11, 13, 17, 19, 29, 31, 41, 59, 71, 101, 107, 109, 137, 139, 149, 179, 181, 191, 197, 199, 227, 239, 269, 281, 311, 347, 419, 431, 461, 521, 569, 571, 599, 617, 641, 659, 809, 811, 821, 827, 829, 857, 881, 1019, 1031, 1049, 1061, 1091, 1151, 1229 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE (3, 5) are twin numbers and also Chen numbers. MAPLE 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_twin_primes:=proc(n) local i, ans; ans:=[ ]: for i from 1 to n do if (ischenprime(i) = 'true') and (isprime(i+2) = 'true' or isprime(i-2) = 'true') then ans:=[op(ans), i]: fi od; RETURN(ans) end: ts_chen_twin_primes(1230); CROSSREFS Cf. A001097, A109611. Sequence in context: A132143 A239879 A001097 * A179679 A059362 A212376 Adjacent sequences:  A117240 A117241 A117242 * A117244 A117245 A117246 KEYWORD nonn AUTHOR Jani Melik, Apr 22 2006 EXTENSIONS Corrected and extended by Jani Melik, May 04 2013 STATUS approved

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Last modified April 15 20:40 EDT 2021. Contains 342977 sequences. (Running on oeis4.)