A118494 Palindromic primes that are not Chen primes.
151, 313, 373, 383, 727, 757, 929, 10501, 11311, 12421, 13831, 14341, 15451, 17971, 18181, 18481, 19391, 19891, 30103, 30203, 30403, 30703, 30803, 31513, 32323, 32423, 33533, 34543, 34843, 35053, 35153, 35353, 36563, 37273, 37573, 38083
Offset: 1
Programs
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Maple
# Check if number is Chen prime 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: # Check if number is palindrome ts_numpal:=proc(n) local ad; ad:=convert(n, base, 10): if (ListTools[Reverse](ad)=ad) then return 'true' else return 'false' fi end: ts_pal_nonchen:=proc(n) local i,ans; ans:=[ ]: for i from 1 to n do if (ischenprime(i) = 'false' and ts_numpal(i) = 'true') then ans:=[op(ans),i]: fi od: return ans end: ts_pal_nonchen(100000);
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Mathematica
Select[ Prime[ Range[5000]], PalindromeQ [#]&&!PrimeQ[ # + 2] &&!PrimeOmega[ #+2]==2 &] (* James C. McMahon, Mar 29 2024 *)