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A178723
Pseudoprimes to base 2 of the form 4k+1.
2
341, 561, 645, 1105, 1729, 1905, 2465, 2701, 2821, 3277, 4033, 4369, 4681, 5461, 6601, 7957, 8321, 8481, 10261, 10585, 11305, 12801, 13741, 13981, 15709, 15841, 16705, 18705, 18721, 23001, 23377, 25761, 29341, 30121, 30889, 31417, 31609, 31621, 33153, 34945, 35333, 39865, 41041, 41665, 46657, 49141, 49981, 52633
OFFSET
1,1
LINKS
MATHEMATICA
Select[4 * Range[10^4] + 1, CompositeQ[#] && PowerMod[2, # - 1, #] == 1 &] (* Amiram Eldar, Sep 10 2019 *)
PROG
(PARI) forstep(n=5, 10^7, 4, if(isprime(n), next()); if(Mod(2, n)^(n-1)==1, print1(n, ", ")))
CROSSREFS
Sequence in context: A253038 A271873 A001567 * A210993 A346567 A328691
KEYWORD
nonn
AUTHOR
Joerg Arndt, Dec 30 2010
STATUS
approved