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A275681
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Table read by rows: list of sexy prime triples (p, p+6, p+12) such that p+18 is composite.
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2
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7, 13, 19, 17, 23, 29, 31, 37, 43, 47, 53, 59, 67, 73, 79, 97, 103, 109, 101, 107, 113, 151, 157, 163, 167, 173, 179, 227, 233, 239, 257, 263, 269, 271, 277, 283, 347, 353, 359, 367, 373, 379, 557, 563, 569, 587, 593, 599, 607, 613, 619, 647, 653, 659, 727, 733, 739
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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The table starts:
7, 13, 19;
17, 23, 29;
31, 37, 43;
...
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MAPLE
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N:= 10^4: # to get all entries <= N
Primes:= select(isprime, {seq(i, i=1..N+18, 2)}):
S:= select(`<=`, Primes, N) intersect map(t -> t-6, Primes) intersect map(t -> t-12, Primes) minus map(t -> t-18, Primes):
map(t ->(t, t+6, t+12), sort(convert(S, list))); # Robert Israel, Aug 05 2016
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MATHEMATICA
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Most[#]&/@Select[Table[n+{0, 6, 12, 18}, {n, Prime[Range[200]]}], PrimeQ[#] == {True, True, True, False}&]//Flatten (* Harvey P. Dale, Jan 19 2017 *)
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PROG
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(Magma) lst:=[]; for p in PrimesUpTo(727) do b:=p+6; if IsPrime(b) then c:=b+6; if IsPrime(c) and not IsPrime(c+6) then lst:=lst cat [p, b, c]; end if; end if; end for; lst;
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CROSSREFS
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KEYWORD
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nonn,tabf
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AUTHOR
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STATUS
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approved
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