OFFSET
1,1
COMMENTS
Corresponding semiprimes n^4+1 are in A186688.
LINKS
Robert Price, Table of n, a(n) for n = 1..1500
EXAMPLE
3 is in the sequence because 3^4 + 1 = 82 = 2*41 is semiprime.
MATHEMATICA
SemiPrimeQ[ n_] := (n > 1) && (2 == Plus @@ (Transpose[FactorInteger[n]][[2]]));
Select[Range[300], SemiPrimeQ[#^4 + 1] &]
Select[Range[200], PrimeOmega[#^4+1]==2&] (* Harvey P. Dale, Jan 27 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Feb 25 2011
STATUS
approved