A014232 Primes of the form 3^k - 2.

7, 79, 241, 727, 19681, 31381059607, 450283905890997361, 36472996377170786401, 8727963568087712425891397479476727340041447, 4638397686588101979328150167890591454318967698007

Offset: 1

Author

Jud McCranie

Keywords

• nonn

References

• Daniel Minoli, Voice over MPLS, McGraw-Hill, New York, NY, 2002, ISBN 0-07-140615-8 (p.114-134) [From Daniel Minoli (daniel.minoli(AT)ses.com), Aug 26 2009]

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..20
• Daniel Minoli, W. Nakamine, Mersenne Numbers Rooted On 3 For Number Theoretic Transforms, 1980 IEEE International Conf. on Acoust., Speech and Signal Processing. [From Daniel Minoli (daniel.minoli(AT)ses.com), Aug 26 2009]
• Daniel Minoli, Issues In Non-Linear Hyperperfect Numbers, Mathematics of Computation, Vol. 34, No. 150, April 1980, pp. 639-645. [From Daniel Minoli (daniel.minoli(AT)ses.com), Aug 26 2009]

Crossrefs

Cf. A000040, A007593, A014224 (corresponding k's).

Programs

Magma

[a: n in [1..200] | IsPrime(a) where a is 3^n-2]; // Vincenzo Librandi, Dec 07 2011

Mathematica

lst={};Do[p=3^n;If[PrimeQ[p-2],AppendTo[lst,p-2]],{n,2*5!}];lst (* Vladimir Joseph Stephan Orlovsky, May 14 2010 *)
Select[3^Range[120]-2,PrimeQ] (* Harvey P. Dale, Aug 16 2011 *)

PARI

for(n=2,1e3,if(ispseudoprime(t=3^n-2),print1(n", "))) \\ Charles R Greathouse IV, Dec 07 2011

Formula

a(n) = 3^A014224(n) - 2. - Elmo R. Oliveira, Nov 09 2023