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A260828
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Primes that contain only the digits (1, 5, 7).
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3
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5, 7, 11, 17, 71, 151, 157, 557, 571, 577, 751, 757, 1117, 1151, 1171, 1511, 1571, 1777, 5171, 5557, 5711, 5717, 7151, 7177, 7517, 7577, 7717, 7757, 11117, 11171, 11177, 11551, 11717, 11777, 15511, 15551, 17117, 17551, 51151, 51157, 51511, 51517, 51551, 51577
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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Select[Prime[Range[2 10^4]], Complement[IntegerDigits[#], {1, 5, 7}] == {} &]
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PROG
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(Magma) [p: p in PrimesUpTo(2*10^5) | Set(Intseq(p)) subset [1, 5, 7]];
(Python)
from sympy import isprime
from sympy.utilities.iterables import multiset_permutations
def aupton(terms):
n, digits, alst = 0, 1, []
while len(alst) < terms:
mpstr = "".join(d*digits for d in "157")
for mp in multiset_permutations(mpstr, digits):
t = int("".join(mp))
if isprime(t): alst.append(t)
if len(alst) == terms: break
else: digits += 1
return alst
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CROSSREFS
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Cf. similar sequences listed in A260827.
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KEYWORD
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nonn,easy,base
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AUTHOR
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STATUS
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approved
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