OFFSET
1,1
COMMENTS
n^8 + 1 is an irreducible polynomial over the integers and thus can be prime (1^8+1=2, 2^8+1=257, 4^8+1=65537) as well as semiprime.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
FORMULA
a(n)^8+1 is an element of A001538.
EXAMPLE
6^8+1 = 1679617 = 17 * 98801,
16^8+1 = 4294967297 = 641 * 6700417,
72^8+1 = 722204136308737 = 12110113 * 59636449 where the two factors have the same number of digits.
MATHEMATICA
fQ[n_] := Flatten[ Table[ #[[2]], {1}] & /@ FactorInteger[n]] == {1, 1}; Select[ Range[220], fQ[ #^8 + 1] &] (* Robert G. Wilson v, Apr 06 2005 *)
Select[Range[300], PrimeOmega[#^8+1]==2&] (* Harvey P. Dale, Nov 19 2018 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Apr 05 2005
EXTENSIONS
More terms from Robert G. Wilson v, Apr 06 2005
STATUS
approved