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 A118725 Chen primes for which the reversal is also a Chen prime. 3
 2, 3, 5, 7, 11, 13, 17, 31, 71, 101, 107, 113, 131, 149, 157, 167, 179, 181, 191, 199, 311, 347, 353, 359, 389, 701, 743, 751, 761, 787, 797, 919, 941, 953, 971, 983, 991, 1009, 1031, 1061, 1091, 1097, 1109, 1151, 1217, 1229, 1259, 1283, 1301, 1409, 1439 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE 17 and its reversal 71 are both Chen primes. MAPLE revdigs:= proc(n) local L, k;   L:= convert(n, base, 10);   add(L[-k]*10^(k-1), k=1..nops(L)) end proc: filter:= proc(n) local r;   if not isprime(n) then return false fi;   r:= revdigs(n);   isprime(r) and numtheory:-bigomega(n+2) <= 2 and numtheory:-bigomega(r+2) <= 2 end proc: select(filter, [2, seq(i, i=3..2000, 2)]); # Robert Israel, Jun 16 2020 MATHEMATICA cpQ[n_]:=Module[{rev=FromDigits[Reverse[IntegerDigits[n]]]}, PrimeOmega[ n+2]<3 && PrimeQ[rev]&&PrimeOmega[rev+2]<3]; Select[Prime[ Range[ 400]], cpQ] (* Harvey P. Dale, Jul 17 2011 *) CROSSREFS Cf. A109611. Sequence in context: A253717 A186307 A321420 * A117835 A120639 A141263 Adjacent sequences:  A118722 A118723 A118724 * A118726 A118727 A118728 KEYWORD base,nonn,less AUTHOR Luc Stevens (lms022(AT)yahoo.com), May 21 2006 EXTENSIONS Corrected by Harvey P. Dale, Jul 17 2011 STATUS approved

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Last modified September 30 11:55 EDT 2020. Contains 337439 sequences. (Running on oeis4.)