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A214705
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Primes that contain only the digits (2, 5, 7).
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2
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2, 5, 7, 227, 257, 277, 557, 577, 727, 757, 2557, 2777, 5227, 5527, 5557, 7577, 7727, 7757, 22277, 22727, 22777, 25577, 27277, 27527, 52727, 52757, 57527, 57557, 57727, 72227, 72277, 72577, 72727, 75227, 75277, 75527, 75557, 75577, 77527, 77557, 222527, 222557
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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The digits are prime numbers.
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LINKS
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MATHEMATICA
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Flatten[Table[Select[FromDigits/@Tuples[{2, 5, 7}, n], PrimeQ], {n, 6}]]
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PROG
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(Magma) [p: p in PrimesUpTo(100000) | Set(Intseq(p)) subset [2, 5, 7]];
(Python)
from sympy import primerange
def ok(p): return set(str(p)) <= set("257")
def aupto(limit): return [p for p in primerange(2, limit+1) if ok(p)]
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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