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17, 107, 113, 167, 179, 389, 1031, 1091, 1097, 1109, 1181, 1259, 1439, 1487, 1523, 1583, 1619, 1847, 3023, 3089, 3257, 3347, 3359, 3527, 3719, 7349, 7529, 7577, 7589, 7649, 7949, 9029, 10067, 10151, 10247, 10487, 10739, 10781, 11057, 11423, 11621, 11777, 11897, 11933, 12119, 12227, 12641, 13151
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internal format)
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OFFSET
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1,1
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COMMENTS
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Primes p such that the digit-reversal q = A004086(p) is a prime greater than p, and p+q = x*y for some x and y such that x+y and the concatenation x|y are primes.
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LINKS
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EXAMPLE
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a(4) = 167 is a term because 167 and 761 are primes with 167 < 761, and 167+761 = 928 = 32*29 with 3229 and 32+29 = 61 prime.
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MAPLE
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revdigs:= proc(n) local L, i;
L:= convert(n, base, 10);
add(L[-i]*10^(i-1), i=1..nops(L))
end proc:
filter:= proc(p) local q, m, d, e;
q:= revdigs(p); if q <= p then return false fi;
if not isprime(p) or not isprime(q) then return false fi;
m:= p+q;
for d in numtheory:-divisors(m) do
e:= m/d;
if isprime(d*10^(1+ilog10(e))+e) and isprime(d+e) then return true fi
od;
false
end proc:
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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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