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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A050587 Numbers n such that 123*2^n-1 is prime. 0
2, 3, 11, 15, 23, 24, 27, 35, 71, 84, 108, 122, 123, 138, 236, 242, 290, 392, 500, 611, 747, 771, 1106, 1490, 3560, 5111, 6066, 8660, 8927, 19451, 19730, 28316, 30471, 49515, 93762, 117083, 168435, 206663, 249242, 255402, 261530, 355727, 389052, 516456, 518540, 521031 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..46.

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300

Wilfrid Keller, List of primes k.2^n - 1 for k < 300

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

Kosmaj, Riesel list k<300.

PROG

(PARI) is(n)=ispseudoprime(123*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A036972 A041637 A042235 * A293026 A178430 A295128

Adjacent sequences:  A050584 A050585 A050586 * A050588 A050589 A050590

KEYWORD

hard,nonn

AUTHOR

N. J. A. Sloane, Dec 29 1999

EXTENSIONS

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

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 October 20 20:24 EDT 2019. Contains 328273 sequences. (Running on oeis4.)