A300010 Numbers k such that 3^k + k - 1 is a prime.

1, 3, 65, 123, 435, 465, 677, 947, 4215, 5615, 69749

Offset: 1

Author

Vincenzo Librandi, Apr 01 2018

Keywords

• nonn
• more

Comments

Corresponding primes: 3, 29, 10301051460877537453973547267907, 48519278097689642681155855396759336072749841943521979872949, ...

a(12), if it exists, is greater than 100000. - Michael S. Branicky, Oct 09 2024

Crossrefs

Cf. A173063, A301632.

Programs

Magma

[k: k in [1..700] | IsPrime(3^k+k-1)];

Maple

select(k->isprime(3^k+k-1),[$1..1000]); # Muniru A Asiru, Apr 05 2018

Mathematica

Flatten[{Select[Range[6000], PrimeQ[3^# + # - 1] &]}]

PARI

lista(nn) = forstep(n=1, nn, 2, if(ispseudoprime(3^n + n - 1), print1(n, ", "))); \\ Altug Alkan, Apr 01 2018

Extensions

a(11) from Michael S. Branicky, Oct 08 2024