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A090649
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Numbers n such that 9^n + 2 is prime.
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6
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0, 1, 2, 4, 5, 7, 12, 13, 18, 49, 55, 63, 193, 247, 610, 929, 2173, 3479, 5494, 11158, 16754, 30920, 47752, 50702, 53725, 68122, 89214
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| All terms are the exact halves of the even terms in A051783. - Alexander Adamchuk (alex(AT)kolmogorov.com), Mar 02 2008
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LINKS
| Henri & Renaud Lifchitz, PRP Records.
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EXAMPLE
| 9^13 + 2 = 2541865828331 is prime.
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MATHEMATICA
| Do[ If[ PrimeQ[9^n + 2], Print[n]], {n, 1, 2250}] (from Robert G. Wilson v Feb 06 2004)
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PROG
| (PARI) for(i=0, 700, if(isprime(9^i+2), print(i)))
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CROSSREFS
| Cf. A051783 = Numbers n such that 3^n + 2 is prime. Cf. A087885 = Numbers n such that 5^n + 2 is prime.
Sequence in context: A022439 A050134 A010065 * A154686 A165196 A007062
Adjacent sequences: A090646 A090647 A090648 * A090650 A090651 A090652
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KEYWORD
| nonn
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AUTHOR
| Herman H. Rosenfeld (herm3(AT)pacbell.net), Feb 02 2004
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EXTENSIONS
| More terms from mohammed bouayoun (bouyao(AT)wanadoo.fr), Feb 04 2004
Further terms from Robert G. Wilson v (rgwv(AT)rgwv.com) and Ray Chandler (rayjchandler(AT)sbcglobal.net), Feb 06 2004
a(20) - a(22) found by Henri Lifchitz, a(23) found by Wojciech Florek. - Jason Earls (zevi_35711(AT)yahoo.com), Feb 25 2008
a(24)-a(27) from A051783 by Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 06 2011
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