

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
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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)];


CROSSREFS



KEYWORD

nonn,more


AUTHOR



STATUS

approved



