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A056797
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Numbers n such that 9*10^n+1 is prime.
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7
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3, 4, 5, 9, 22, 27, 36, 57, 62, 78, 201, 537, 696, 790, 905, 1038, 66886, 70500, 91836
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..19.
Makoto Kamada, Factorizations of 900...001.
Sabin Tabirca and Kieran Reynolds, Lacunary Prime Numbers.
Index entries for primes involving repunits.
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EXAMPLE
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For n=9 we have (9*(10^9))+1 = 9000000001, which is prime.
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MATHEMATICA
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Do[ If[ PrimeQ[9*10^n + 1], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Cf. A056806 = 4*10^n+1 is prime.
Sequence in context: A195971 A080552 A215176 * A029727 A086186 A014463
Adjacent sequences: A056794 A056795 A056796 * A056798 A056799 A056800
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KEYWORD
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more,nonn
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AUTHOR
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Robert G. Wilson v, Aug 22 2005
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EXTENSIONS
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a(18)-a(19) from Kamada data by Robert Price, Dec 14 2010
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STATUS
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approved
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