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A101393
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Numbers n such that 3*10^n + R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
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1
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OFFSET
| 1,2
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COMMENTS
| Also numbers such that (28*10^n+53)/9 is prime.
All except 1, 2 and 218 only probably prime. No others less than 10000.
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LINKS
| Makoto Kamada, Factorizations of 311...117.
Index entries for primes involving repunits.
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EXAMPLE
| n = 1, 2 are members since 37 and 317 are primes.
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MATHEMATICA
| Do[ If[ PrimeQ[(28*10^n+53)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
| Cf. A100501, A100473.
Sequence in context: A078280 A125058 A202741 * A124188 A078276 A117076
Adjacent sequences: A101390 A101391 A101392 * A101394 A101395 A101396
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KEYWORD
| nonn
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AUTHOR
| Julien Peter Benney (jpbenney(AT)ftml.net), Jan 15 2005
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EXTENSIONS
| a(8) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 13 2010
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