Search: id:A076612
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%I A076612
%S A076612 1,4,6,8,9,101,111,141,161,181,191,202,212,242,262,282,292,303,313,343,
%T A076612 363,383,393,404,414,444,464,484,494,505,515,545,565,585,595,606,616,
%U A076612 646,666,686,696,707,717,747,767,787,797,808,818,848,868,888,898,909
%N A076612 Palindromic numbers with nonprime middle digit.
%e A076612 a(12)=202=2*101 is palindromic number and its middle digit 0 is not prime, 
               a(13)=212=2^2*53 is palindromic number and its middle digit 1 is 
               not prime, a(14)=242=2*11^2 is palindromic number and its middle 
               digit 4 is not prime, ...
%p A076612 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_n_pal := proc(n) 
               if ts_num_midpal(n) = 0 then return (i) fi end: anpal := [seq(ts_n_pal(i), 
               i=1..50000)]: anpal;
%Y A076612 Cf. A002113.
%Y A076612 Sequence in context: A113624 A113591 A029581 this_sequence A046354 A046357 
               A144123
%Y A076612 Adjacent sequences: A076609 A076610 A076611 this_sequence A076613 A076614 
               A076615
%K A076612 easy,nonn,base
%O A076612 1,2
%A A076612 Jani Melik (jani_melik(AT)hotmail.com), Oct 21 2002

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