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Search: id:A123924
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| A123924 |
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Numbers n such that 2^(n+1) + 3^n is prime. |
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+0
1
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| 0, 1, 2, 3, 4, 5, 6, 9, 11, 12, 15, 17, 22, 32, 33, 35, 36, 46, 47, 59, 63, 80, 101, 154, 159, 173, 221, 225, 236, 250, 281, 347, 789, 992, 1607, 1631, 1983, 2072, 3616, 3702, 5076, 5957, 6335
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OFFSET
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1,3
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COMMENT
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Also numbers n such that A123601(n) = A085279(n+1) = 2^(n+1) + 3^n. There are only 4 known primes of form the 2^k + 3^k, {2, 5, 13, 97} = A082101(n), corresponding to k = {0, 1, 2, 4}.
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MATHEMATICA
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Do[f=2^(n+1)+3^n; If[PrimeQ[f], Print[{n, f}]], {n, 0, 347}]
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CROSSREFS
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Cf. A123601 = Smallest prime of the form p^n + q^n + r^n, where p, q, r are primes. Cf. A085279 = 2^n + 3^(n-1). Cf. A082101 = Primes of form 2^k + 3^k.
Sequence in context: A116546 A108957 A080112 this_sequence A036023 A119952 A102571
Adjacent sequences: A123921 A123922 A123923 this_sequence A123925 A123926 A123927
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KEYWORD
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nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Nov 20 2006
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 12 2007
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