A082102 Primes of the form 2^(k-1) + 3^k.

11, 31, 89, 761, 2251, 6689, 59561, 14365291, 10461401779, 282437925089, 150094669656737489, 239299329512092506300739, 2153693964201457673153371, 107752636643058216783050887908587014548761

Offset: 1

Author

Labos Elemer, Apr 14 2003

Keywords

• nonn

Examples

			89 = 2^3 + 3^4.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..30

Crossrefs

Cf. A082101, A082103.

Programs

Mathematica

Do[s=2^(w-1)+3^w; If[PrimeQ[s], Print[s]], {w, 1, 2000}]
Select[Table[2^(n-1)+3^n,{n,100}],PrimeQ] (* Harvey P. Dale, Feb 09 2016 *)

PARI

lista(kmax) = {my(p); for(k = 1, kmax, p = 2^(k-1) + 3^k; if(isprime(p), print1(p, ", ")));} \\ Amiram Eldar, Aug 16 2024

Formula

a(n) = 2^(A082103(n)-1) + 3^A082103(n). - Amiram Eldar, Aug 16 2024