OFFSET
1,2
COMMENTS
a(8) > 413. - Carl Schildkraut, Aug 14 2015
a(10) >= 766. - Kevin P. Thompson, May 01 2022
LINKS
EXAMPLE
1 is in this sequence because 5^1+1 = 2*3 is semiprime.
8 is in this sequence because 5^8+8 = 3*130211 and these two factors are prime.
MATHEMATICA
Select[Range[413], PrimeOmega[5^# + #]==2 &]
PROG
(Magma) IsSemiprime:=func<i | &+[d[2]: d in Factorization(i)] eq 2>; [m: m in [1..110] | IsSemiprime(s) where s is 5^m+m];
(PARI) main(m)=select(m->bigomega(5^m + m)==2, vector(m, i, i)); \\ Anders Hellström, Aug 14 2015
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Vincenzo Librandi, Dec 24 2014
EXTENSIONS
a(5)-a(7) from Carl Schildkraut, Aug 14 2015
a(8)-a(9) from Kevin P. Thompson, May 01 2022
STATUS
approved