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A270102 Numbers n such that 3^n - n*2^n is prime. 2
3, 4, 5, 7, 8, 10, 11, 23, 34, 62, 95, 128, 173, 251, 260, 464, 628, 1267, 1895, 2057, 2743, 5102, 7790, 49163 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..24.

EXAMPLE

n = 4 is a term since 3^4 - 4*2^4 = 17 is prime.

MAPLE

A270102:=n->`if`(isprime(3^n-n*2^n), n, NULL): seq(A270102(n), n=1..2000); # Wesley Ivan Hurt, May 08 2016

MATHEMATICA

Select[Range[1, 1000], PrimeQ[3^# - #*2^#] &] (* Vaclav Kotesovec, Mar 11 2016 *)

PROG

(MATLAB)

if isprime(3^n - n*2^n)

disp(n)

end

(Python)

from gmpy2 import is_prime

for n in range(5000):

   if(is_prime(3**n-n*2**n)):print(n, end=", ")

# Soumil Mandal, May 08 2016

(PARI) is(n)=ispseudoprime(3^n-n*2^n) \\ Charles R Greathouse IV, Jun 06 2017

CROSSREFS

Cf. A057468, A270104.

Sequence in context: A287127 A174681 A267650 * A026347 A187482 A285950

Adjacent sequences:  A270099 A270100 A270101 * A270103 A270104 A270105

KEYWORD

nonn,more

AUTHOR

Vardan Semerjyan, Mar 11 2016

EXTENSIONS

a(24) from Giovanni Resta, May 05 2016

STATUS

approved

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Last modified August 1 17:43 EDT 2021. Contains 346402 sequences. (Running on oeis4.)