OFFSET
1,1
COMMENTS
From Kevin P. Thompson, May 01 2022: (Start)
a(15) >= 335.
391, 443, 607, 683, 737, and 745 are also terms in this sequence. (End)
LINKS
EXAMPLE
2 is in this sequence because 6^2+2 = 2*19 is semiprime.
7 is in this sequence because 6^7+7 = 271*1033 and these two factors are prime.
MATHEMATICA
Select[Range[90], PrimeOmega[6^# + #]==2 &]
PROG
(Magma) IsSemiprime:=func<i | &+[d[2]: d in Factorization(i)] eq 2>; [m: m in [1..90] | IsSemiprime(s) where s is 6^m+m];
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Vincenzo Librandi, Dec 25 2014
EXTENSIONS
a(10)-a(14) by Luke March, Jul 08 2015
STATUS
approved