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 A118494 Palindromic primes that are not Chen primes. 0
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..36. 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); MATHEMATICA Select[ Prime[ Range[5000]], PalindromeQ [#]&&!PrimeQ[ # + 2] &&!PrimeOmega[ #+2]==2 &] (* James C. McMahon, Mar 29 2024 *) CROSSREFS Cf. A002385, A109574, A109611. Sequence in context: A142760 A142903 A031893 * A140022 A211551 A108842 Adjacent sequences: A118491 A118492 A118493 * A118495 A118496 A118497 KEYWORD nonn,base,less AUTHOR Jani Melik, May 05 2006 STATUS approved

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Last modified June 15 15:25 EDT 2024. Contains 373407 sequences. (Running on oeis4.)