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A123924
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Numbers k such that 2^(k+1) + 3^k is prime.
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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, 8771, 10203, 10984, 12203, 12350, 13660, 14891
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OFFSET
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1,3
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COMMENTS
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Also numbers k such that A123601(k) = A085279(k+1) = 2^(k+1) + 3^k. There are only 4 known primes of form the 2^k + 3^k, {2, 5, 13, 97} = A082101, corresponding to k = {0, 1, 2, 4}.
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LINKS
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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}]
Select[Range[0, 6400], PrimeQ[2^(#+1)+3^#]&] (* Harvey P. Dale, Mar 04 2019 *)
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PROG
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CROSSREFS
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Cf. A082101 (primes of form 2^k + 3^k), A085279, A123601 (smallest prime of the form p^n + q^n + r^n, where p,q,r are primes).
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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