Search: id:A076613
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%I A076613
%S A076613 101,181,191,313,383,787,797,919,10601,11411,12421,12821,13831,13931,
%T A076613 15451,16061,16661,17471,17971,18181,18481,19891,19991,30103,30403,
%U A076613 30803,31013,32423,34843,35053,35153,38083,38183,70607,71917,73037
%N A076613 Palindromic primes with nonprime middle digit.
%e A076613 a(12)=12821 is palindromic prime and its middle digit 8 is not prime, 
               a(13)=13831 is palindromic prime and its middle digit 8 is not prime, 
               a(14)=13931 is palindromic prime and its middle digit 9 is not prime, 
               ...
%p A076613 ts_num_midpal := proc(n) local ad,adr,midigit; ad := convert(n,base,10): 
               adr := ListTools[Reverse](ad): if nops(ad) mod 2 = 0 then return 
               1; fi; midigit := op( (nops(ad)+1)/2,ad ): if (isprime( midigit )='false' 
               and adr=ad) then return 0; else return 1; fi end: ts_pra_n_pal := 
               proc(n) local p1; p1 := ithprime(n): if ts_num_midpal(p1) = 0 then 
               return (p1) fi end: apranpal := [seq(ts_pra_n_pal(i), i=1..100000)]: 
               apranpal;
%Y A076613 Cf. A002385, A069217.
%Y A076613 Sequence in context: A067860 A140037 A107209 this_sequence A045978 A141913 
               A100775
%Y A076613 Adjacent sequences: A076610 A076611 A076612 this_sequence A076614 A076615 
               A076616
%K A076613 easy,nonn,base
%O A076613 1,1
%A A076613 Jani Melik (jani_melik(AT)hotmail.com), Oct 21 2002

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