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A085746
Numbers n such that n^2 + n + 1 is a semiprime.
1
4, 7, 9, 10, 11, 13, 19, 23, 26, 28, 29, 31, 32, 34, 35, 36, 39, 40, 42, 43, 44, 45, 47, 48, 51, 52, 53, 56, 60, 63, 65, 70, 72, 73, 76, 82, 83, 84, 85, 86, 91, 92, 93, 95, 96, 97, 98, 103, 104, 108, 112, 113, 114, 115, 120, 122, 123, 124, 125, 126, 127, 129, 132, 134
OFFSET
1,1
LINKS
MATHEMATICA
lst={}; Do[If[Plus@@Last/@FactorInteger[n^2 + n + 1] == 2, AppendTo[lst, n]], {n, 0, 150}]; lst (* Vincenzo Librandi, Sep 22 2012 *)
Select[Range[150], PrimeOmega[#^2+#+1]==2&] (* Harvey P. Dale, Dec 07 2012 *)
CROSSREFS
Sequence in context: A046254 A268227 A123573 * A324599 A081828 A287678
KEYWORD
nonn
AUTHOR
Jason Earls, Jul 21 2003
STATUS
approved