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#19 by N. J. A. Sloane at Sun Aug 11 14:41:30 EDT 2024
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| LINKS
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P. De Geest, <a href="httphttps://www.worldofnumbers.com/palpri.htm">World!Of Palindromic Primes</a>
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Discussion
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Sun Aug 11
| 14:41
| OEIS Server: https://oeis.org/edit/global/2998
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#18 by R. J. Mathar at Sat Oct 17 18:09:23 EDT 2015
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#17 by R. J. Mathar at Sat Oct 17 18:08:52 EDT 2015
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#16 by Giovanni Resta at Wed Aug 19 06:02:21 EDT 2015
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#15 by Michel Marcus at Wed Aug 19 05:09:35 EDT 2015
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#14 by Robert Israel at Wed Aug 19 02:51:54 EDT 2015
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#13 by Robert Israel at Wed Aug 19 02:50:54 EDT 2015
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| MAPLE
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N:= 14: # to get all terms < 3^N
Res:= 2:
digrev:=proc(n) local L;
L:= convert(n, base, 3);
add(L[-i]*3^(i-1), i=1..nops(L))
end proc;
for d from 2 to N do
if d::even then
m:= d/2;
Res:= Res, op(select(isprime, [seq](n*3^m + digrev(n), n=3^(m-1)..3^m-1)));
else
m:= (d-1)/2;
Res:= Res, op(select(isprime, [seq](seq(n*3^(m+1)+y*3^m+digrev(n),
y=0..2), n=3^(m-1)..3^m-1)));
fi
od:
Res; # Robert Israel, Aug 19 2015
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| STATUS
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reviewed
editing
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#12 by Joerg Arndt at Wed Aug 19 02:23:40 EDT 2015
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#11 by Michel Marcus at Wed Aug 19 02:00:12 EDT 2015
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#10 by Michel Marcus at Wed Aug 19 01:59:56 EDT 2015
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