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A180748 Numbers k such that k^2 - k + 1 is semiprime. 2
5, 8, 10, 11, 12, 14, 20, 24, 27, 29, 30, 32, 33, 35, 36, 37, 40, 41, 43, 44, 45, 46, 48, 49, 52, 53, 54, 57, 61, 64, 66, 71, 73, 74, 77, 83, 84, 85, 86, 87, 92, 93, 94, 96, 97, 98, 99, 104, 105, 109, 113, 114, 115, 116, 121, 123, 124, 125, 126, 127, 128, 130, 133, 135 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MATHEMATICA
Select[Range[135], PrimeOmega[#^2 - # + 1] == 2 &] (* Amiram Eldar, Dec 23 2019 *)
CROSSREFS
Sequence in context: A331442 A006186 A230457 * A350377 A121901 A024707
KEYWORD
easy,nonn
AUTHOR
Jason Earls, Sep 19 2010
STATUS
approved

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Last modified March 28 17:42 EDT 2024. Contains 371254 sequences. (Running on oeis4.)