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Search: id:A101783
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| A101783 |
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Lower bound twin primes such that their digital reverse is prime and a lower bound twin prime. |
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+0
1
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| 3, 5, 11, 17, 71, 101, 191, 1031, 1301, 7349, 7457, 7547, 7589, 9437, 9857, 10007, 10067, 10301, 10457, 10859, 11057, 11717, 11777, 11939, 12107, 12821, 13931, 14081, 14549, 14591, 16061, 16361, 16829, 17417, 18041, 19541, 19697, 19991
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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17 is a lower bound twin prime and the reverse,71, is prime and also a lower bound twin prime.
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PROGRAM
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(PARI) twlrpr2(n) = { for(x=1, n, y=twinl(x); z=eval(rev(y)); if(isprime(z)&isprime(z+2), print1(y", ")) ) } twinl(n) = \The n-th upper twin prime { local(c, x); c=0; x=1; while(c<n, if(isprime(prime(x)+2), c++); x++; ); return(prime(x)) } rev(str) = \ Get the reverse of the input string { local(tmp, s, j); tmp = Vec(Str(str)); s=""; forstep(j=length(tmp), 1, -1, s=concat(s, tmp[j])); return(s) }
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CROSSREFS
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Sequence in context: A147251 A146473 A101781 this_sequence A078883 A109556 A090952
Adjacent sequences: A101780 A101781 A101782 this_sequence A101784 A101785 A101786
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KEYWORD
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easy,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Jan 26 2005
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