A252794 Numbers m such that 9^m + m is a semiprime.

1, 5, 68, 85, 86, 92, 136

Offset: 1

Author

Vincenzo Librandi, Dec 27 2014

Keywords

• nonn
• more

Comments

a(8) > 435. - Carl Schildkraut, Aug 14 2015

Examples

			1 is in this sequence because 9^1+1 = 2*5 is semiprime.
5 is in this sequence because 9^5+5 = 2*29527 and these two factors are prime.
		

Crossrefs

Cf. similar sequences listed in A252788.

Cf. A252662.

Programs

Magma

IsSemiprime:=func; [m: m in [1..435] | IsSemiprime(s) where s is 9^m+m];

Mathematica

Select[Range[435], PrimeOmega[9^# + #]==2 &]

Extensions

a(4)-a(7) from Carl Schildkraut, Aug 14 2015