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A128335
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Numbers n such that (4^n + 5^n)/9 is prime.
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20
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5, 7, 19, 29, 61, 137, 883, 1381, 1823, 5227, 25561, 29537, 300893
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| All terms are primes.
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LINKS
| Top probable primes of the form (5^p+4^p)/9
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MATHEMATICA
| k=4; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]
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PROG
| (PARI) forprime(p=3, 1e4, if(ispseudoprime((5^p+4^p)/9), print1(p", "))) \\ Charles R Greathouse IV, Jul 16, 2011
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CROSSREFS
| Sequence in context: A094963 A045446 A106074 * A023246 A022889 A001562
Adjacent sequences: A128332 A128333 A128334 * A128336 A128337 A128338
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KEYWORD
| hard,more,nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 27 2007
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EXTENSIONS
| 3 more terms from Ryan Propper (rpropper(AT)cs.stanford.edu), Feb 06 2008
Two more terms from Ryan Propper (rpropper(AT)cs.stanford.edu), May 02 2010
New term 300893 found by Jean-Louis Charton in November 2011 corresponding to a probable prime with 210315 digits.
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