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A333207
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Twin primes whose base-10 digit reversals are also twin primes.
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1
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3, 5, 7, 11, 13, 17, 31, 71, 101, 151, 181, 191, 313, 1031, 1033, 1231, 1279, 1301, 1321, 1429, 1453, 1933, 3301, 3391, 3541, 3583, 3853, 7349, 7457, 7547, 7589, 9241, 9437, 9679, 9721, 9769, 9857, 10007, 10067, 10273, 10301, 10429, 10457, 10501, 10711, 10859, 11057, 11701, 11717, 11777, 11833
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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a(5) = 13 is in the sequence because both 13 and its reversal 31 are twin primes.
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MAPLE
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revdigs:= proc(n) local L, k;
L:= convert(n, base, 10);
add(L[-k]*10^(k-1), k=1..nops(L))
end proc:
Pr:= select(isprime, {seq(i, i=3..10^5, 2)}):
TL:= Pr intersect map(`-`, Pr, 2):
T:= TL union map(`+`, TL, 2):
sort(convert(select(t-> member(revdigs(t), T), T), list));
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MATHEMATICA
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tpQ[p_]:=PrimeQ[IntegerReverse[p]]&&AnyTrue[p+{2, -2}, PrimeQ]; Select[ Prime[ Range[1500]], tpQ[#]&&tpQ[IntegerReverse[#]]&] (* Harvey P. Dale, Jan 16 2022 *)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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