login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A283653 Numbers k such that 3^k + (-2)^k is prime. 4
0, 2, 3, 4, 5, 17, 29, 31, 53, 59, 101, 277, 647, 1061, 2381, 2833, 3613, 3853, 3929, 5297, 7417, 90217, 122219, 173191, 256199, 336353, 485977, 591827, 1059503 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Numbers j such that both 3^j + (-2)^j and 3^j + (-4)^j are primes: 0, 3, 4, 17, 59, ...
See Michael Somos comment in A082101.
Probably this is just A057468 with 0,2,4 added, because we already know that if another even number belong to this sequence it must be greater than log_3(10^16000000) = about 3.3*10^7. This is because 3^n+2^n can be a prime with n>0 only if n is a power of 2. - Giovanni Resta, Mar 12 2017
LINKS
EXAMPLE
4 is in this sequence because 3^4 + (-2)^4 = 97 is prime.
MATHEMATICA
Select[Range[0, 10000], PrimeQ[3^# + (-2)^#] &] (* G. C. Greubel, Jul 29 2018 *)
PROG
(Magma) [n: n in [0..1000] | IsPrime(3^n+(-2)^n)];
(PARI) is(n)=isprime(3^n+(-2)^n) \\ Charles R Greathouse IV, Mar 16 2017
CROSSREFS
Cf. A174326. Subsequence of A087451. Supersequence of A057468.
Cf. A082101.
Sequence in context: A117885 A030574 A325652 * A162657 A333046 A305794
KEYWORD
nonn,more
AUTHOR
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 23 03:03 EST 2024. Contains 370266 sequences. (Running on oeis4.)