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A155762
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Prime numbers p such that prepending any single decimal digit to p does not produce a prime.
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3
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2, 5, 149, 401, 509, 773, 809, 1021, 1103, 1289, 1301, 1451, 1697, 1709, 1747, 1877, 1889, 2087, 2389, 2521, 2663, 3373, 3511, 3631, 3733, 3779, 3821, 3919, 3947, 3989, 4003, 4073, 4241, 4289, 4339, 4637, 4643, 4801, 4931, 5039, 5113, 5387, 5417, 5477
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OFFSET
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1,1
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COMMENTS
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149 is in the sequence, because the following numbers are all composite: 1149, 2149, 3149, 4149, 5149, 6149, 7149, 8149 and 9149.
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LINKS
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MATHEMATICA
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Select[Prime@Range@1000, NoneTrue[#+10^IntegerLength@#*Range@9, PrimeQ]&] (* Hans Rudolf Widmer, May 28 2022 *)
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PROG
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(Python)
from sympy import isprime, primerange
def ok(p): return not any(isprime(int(d+str(p))) for d in "123456789")
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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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