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A301632
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Numbers k such that 3^k + k + 1 is a prime.
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3
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0, 1, 3, 15, 45, 117, 159, 3739, 3777, 9703, 10623, 21459, 86595
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OFFSET
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1,3
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LINKS
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MAPLE
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a:=n->`if`(isprime(3^k+k+1), k, NULL): seq(a(k), k=0..6000); # Muniru A Asiru, Mar 25 2018
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MATHEMATICA
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Flatten[{0, Select[Range[5000], PrimeQ[3^# + # + 1] &]}] (* Vaclav Kotesovec, Mar 25 2018 *)
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PROG
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(PARI) for(n=0, 1000, if(isprime(3^n+n+1), print1(n", ")))
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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