OFFSET
1,2
COMMENTS
The semiprimes of this form are: 9, 129, 1537, 1207959553, 113336795588871485128705, 2535301200456458802993406410753, ...
a(15) >= 483. - Hugo Pfoertner, Aug 05 2019
LINKS
factordb.com, Status of 483*8^483+1.
MATHEMATICA
Select[Range[80], PrimeOmega[# 8^# + 1] == 2 &]
PROG
(Magma) IsSemiprime:=func<i | &+[d[2]: d in Factorization(i)] eq 2>; [n: n in [1..80] | IsSemiprime(s) where s is n*8^n+1];
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Vincenzo Librandi, May 10 2014
EXTENSIONS
a(10)-a(14) from Hugo Pfoertner and Daniel Suteu, Aug 05 2019
STATUS
approved