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Search: id:A128024
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| A128024 |
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Numbers n such that (7^n - 3^n)/4 is prime. |
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21
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OFFSET
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1,1
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COMMENT
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All terms are primes.
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MATHEMATICA
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k=4; Select[ Prime[ Range[1, 200] ], PrimeQ[ ((k+3)^# - 3^#)/k ]& ]
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CROSSREFS
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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. A121977 = numbers n such that (5^n - 3^n)/2 is a prime. Cf. A128025, A128026, A128027, A128028, A128029, A128030, A128031, A128032.
Sequence in context: A049423 A066237 A135741 this_sequence A075487 A118128 A113875
Adjacent sequences: A128021 A128022 A128023 this_sequence A128025 A128026 A128027
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KEYWORD
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hard,more,nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 11 2007
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EXTENSIONS
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2917,5923 from Farideh Firoozbakht (mymontain(AT)yahoo.com), Apr 08 2007
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