login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A309409 Numbers k such that (37^k + 1)/38 is prime. 0
5, 7, 2707, 163193 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Larger terms correspond to probable primes.

LINKS

Table of n, a(n) for n=1..4.

P. Bourdelais, A Generalized Repunit Conjecture

MATHEMATICA

Do[p=Prime[n]; If[PrimeQ[(37^p + 1)/38], Print[p]], {n, 1, 1000000}]

PROG

(PARI) is(n)=ispseudoprime((37^n+1)/38)

CROSSREFS

Sequence in context: A056252 A274774 A176599 * A291687 A257774 A281386

Adjacent sequences:  A309406 A309407 A309408 * A309410 A309411 A309412

KEYWORD

nonn,hard,more

AUTHOR

Paul Bourdelais, Jul 29 2019

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 9 19:51 EST 2019. Contains 329879 sequences. (Running on oeis4.)