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A101398
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Numbers n such that 4*10^n-3 is prime.
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1
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1, 2, 14, 20, 30, 44, 66, 260, 872, 8846, 26744, 57506, 98472, 106892
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history;
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internal format)
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OFFSET
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1,2
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COMMENTS
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See Kamada link for search limit and prime vs. PRP status.
a(14) > 10^5. - Robert Price, Mar 17 2015.
a(15) > 2*10^5. - Robert Price, Oct 02 2015
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LINKS
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Table of n, a(n) for n=1..14.
Makoto Kamada, Prime numbers of the form 399...997.
Index entries for primes involving repunits.
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FORMULA
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a(n) = A101849(n) + 1.
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EXAMPLE
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n = 1, 2, 14, 20 are members since 37, 397, 399999999999997 and 399999999999999999997
are prime numbers.
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MATHEMATICA
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Do[ If[ PrimeQ[4*10^n - 3], Print[n]], {n, 0, 10000}]
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PROG
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(PARI) for(n=1, 1e4, if(isprime(4*10^n-3), print1(n", "))) \\ Altug Alkan, Oct 02 2015
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CROSSREFS
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Cf. A089675, A101849.
Sequence in context: A298002 A217075 A187261 * A131221 A138047 A005237
Adjacent sequences: A101395 A101396 A101397 * A101399 A101400 A101401
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KEYWORD
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nonn
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AUTHOR
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Julien Peter Benney (jpbenney(AT)ftml.net), Jan 15 2005
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EXTENSIONS
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a(11)-a(12) from Kamada data by Robert Price, Dec 13 2010
a(13) from Kamada data by Robert Price, Mar 17 2015
a(14) from Robert Price, Oct 02 2015
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STATUS
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approved
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