A122116 Numbers n such that 2^n+5^n is semiprime.

3, 6, 8, 12, 14, 16, 17, 19, 28, 38, 47, 52, 64, 101, 274

Offset

1,1

Links

Table of n, a(n) for n=1..15.

Prog

(Magma)IsSemiprime:=func< n|&+[ k[2]: k in Factorization(n)] eq 2 >; [ n: n in [2..100]|IsSemiprime(2^n+5^n)]; // Vincenzo Librandi, Dec 16 2010

Crossrefs

Cf. A074600 (2^n + 5^n), A094475 (Primes of form 2^n+5^n).

Sequence in context: A070528 A243117 A356180 * A209885 A126862 A092998

Adjacent sequences: A122113 A122114 A122115 * A122117 A122118 A122119

Keyword

nonn,easy

Author

Zak Seidov, Oct 19 2006

Extensions

a(13), a(14) from D. S. McNeil, Dec 20 2010

Status

approved