Search: id:A088269
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%I A088269
%S A088269 3,5,131,383,797,11411,16061,16361,19391,33533,36263,73037,75557,79397,
%T A088269 1074701,1126211,1145411,1175711,1221221,1243421,1287821,1303031,
%U A088269 1311131,1328231,1363631,1489841,1579751,1600061,1707071,1748471
%N A088269 Palindromic primes that yield a prime when sandwiched between two 1's. 
               (Prefixing and suffixing a one on both sides yields another pal prime).
%C A088269 There are two 1-digit such n's, three 3-digit n's, nine 5-digit n's, 
               93 7-digit n's, 241 9-digit n's and no n with even number of digits. 
               - Zak Seidov (zakseidov(AT)yahoo.com), Feb 23 2005
%e A088269 Start with 11;
%e A088269 insert a(2)=5 between digits of 11, 151 is prime;
%e A088269 insert a(3)=131 between digits of 11, 11311 is prime,
%e A088269 insert a(10)=33533 between digits of 11, 1335331 is prime, etc.
%e A088269 797 is a member as 17971 is also a prime.
%t A088269 Do[If[PrimeQ[n] && Reverse[IntegerDigits[n]] == IntegerDigits[n] && PrimeQ[ToExpression["1" 
               <> ToString[n*10+1]]], Print[n]], {n, 1, 2*10^6}] (Propper)
%Y A088269 Cf. A088270, A088271, A088272.
%Y A088269 Sequence in context: A105526 A070743 A103993 this_sequence A164371 A108013 
               A087307
%Y A088269 Adjacent sequences: A088266 A088267 A088268 this_sequence A088270 A088271 
               A088272
%K A088269 base,nonn
%O A088269 1,1
%A A088269 Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 28 2003
%E A088269 More terms from Ryan Propper (rpropper(AT)stanford.edu), Jul 09 2005
%E A088269 Entry revised by N. J. A. Sloane (njas(AT)research.att.com), Apr 29 2007

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