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 A301632 Numbers k such that 3^k + k + 1 is a prime. 3
 0, 1, 3, 15, 45, 117, 159, 3739, 3777, 9703, 10623, 21459, 86595 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS MAPLE a:=n->`if`(isprime(3^k+k+1), k, NULL): seq(a(k), k=0..6000); # Muniru A Asiru, Mar 25 2018 MATHEMATICA Flatten[{0, Select[Range[5000], PrimeQ[3^# + # + 1] &]}] (* Vaclav Kotesovec, Mar 25 2018 *) PROG (PARI) for(n=0, 1000, if(isprime(3^n+n+1), print1(n", "))) CROSSREFS A182327 gives the primes. Cf. A171058, A173053, A301633. Sequence in context: A050534 A048099 A030505 * A074355 A201868 A260021 Adjacent sequences:  A301629 A301630 A301631 * A301633 A301634 A301635 KEYWORD nonn,more,hard AUTHOR Seiichi Manyama, Mar 25 2018 EXTENSIONS a(8)-a(9) from Muniru A Asiru, Mar 25 2018 a(10)-a(11) from Vaclav Kotesovec, Mar 25 2018 a(12) from Altug Alkan, Apr 01 2018 a(13) from Giovanni Resta, Apr 06 2018 STATUS approved

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Last modified January 19 18:13 EST 2020. Contains 331051 sequences. (Running on oeis4.)