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A128025
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Numbers n such that (8^n - 3^n)/5 is prime.
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20
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OFFSET
| 1,1
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COMMENTS
| All terms are primes.
Verified the first 8 terms in sequence. Also, the next number in the sequence, if one exists is >43691. [From Robert Price, Mar 16 2010]
a(10) > 100,000. [From Robert Price, Jul 27 2011]
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MATHEMATICA
| k=5; Select[ Prime[ Range[1, 200] ], PrimeQ[ ((k+3)^# - 3^#)/k ]& ]
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CROSSREFS
| Cf. A028491 = numbers n such that (3^n - 1)/2 is prime. Cf. A057468 = numbers n such that 3^n - 2^n is prime. Cf. A059801 = numbers n such that 4^n - 3^n is prime. Cf. A121877 = numbers n such that (5^n - 3^n)/2 is a prime. Cf. A128024, A128026, A128027, A128028, A128029, A128030, A128031, A128032.
Sequence in context: A005382 A195354 A113165 * A092064 A152609 A172461
Adjacent sequences: A128022 A128023 A128024 * A128026 A128027 A128028
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KEYWORD
| hard,more,nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 11 2007
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EXTENSIONS
| 9227 from Farideh Firoozbakht (mymontain(AT)yahoo.com), Apr 08 2007
a(9)=43891 from Robert Price (pamandbobprice(AT)yahoo.com), Jul 27 2011
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