OFFSET
1,1
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);
MATHEMATICA
Select[Prime[Range[250]], PrimeOmega[#+2]<3&&AnyTrue[#+{2, -2}, PrimeQ]&] (* Harvey P. Dale, Jul 28 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jani Melik, Apr 22 2006
EXTENSIONS
Corrected and extended by Jani Melik, May 04 2013
STATUS
approved