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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

Table of n, a(n) for n=1..13.

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.)