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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A255682 Numbers n such that 4^n - 2^n - 3 is prime. 0
3, 7, 13, 15, 21, 73, 231, 301, 493, 895, 955, 4069, 5057, 5415, 15325, 19845, 21603, 24577, 37877, 40193, 44283 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..21.

EXAMPLE

3 is in this sequence because 4^3 - 2^3 - 3 = 53.

MATHEMATICA

Select[Range[15000], PrimeQ[4^# - 2^# - 3] &]

PROG

(MAGMA) [n: n in [1..800] | IsPrime(4^n-2^n-3)];

(PARI) for(n=1, 500, if(ispseudoprime(4^n-2^n-3), print1(n, ", "))) \\ Derek Orr, Mar 03 2015

CROSSREFS

Cf. A098845.

Sequence in context: A209839 A192854 A002236 * A080565 A164344 A002254

Adjacent sequences:  A255679 A255680 A255681 * A255683 A255684 A255685

KEYWORD

nonn,more

AUTHOR

Vincenzo Librandi, Mar 02 2015

EXTENSIONS

Added a(15)-a(21), a(22) > 150000. Hans Havermann, Jul 18 2015

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 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)