A291853 Numbers n such that (3^n - (-2)^n)/5 is prime.

3, 4, 7, 11, 83, 149, 223, 599, 647, 1373, 8423

Offset: 1

Author

Juri-Stepan Gerasimov, Sep 04 2017

Keywords

• nonn
• more

Comments

a(12) > 65535. Presumably, a(12) = 149497 and a(13) = 388897.

Examples

			4 is in this sequence because (3^4 - (-2)^4)/5 = 13 is prime.
		

Crossrefs

Supersequence A057469.

Cf. A107036 (numbers n such that (2^n-(-1)^n)/3 is prime).

Programs

Magma

[n: n in [1..1000] | IsPrimePower((3^n-(-2)^n) div 5)];

Mathematica

Select[Range[2000], PrimeQ[(3^# - (-2)^#)/5] &] (* Michael De Vlieger, Dec 09 2017 *)