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A058501
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Primes p such that largest odd factor of p-1 is not a prime (i.e., is composite or 1).
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2
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2, 3, 5, 17, 19, 31, 37, 43, 61, 67, 71, 73, 79, 101, 103, 109, 127, 131, 139, 151, 157, 163, 181, 191, 197, 199, 211, 223, 229, 239, 241, 251, 257, 271, 277, 281, 283, 307, 311, 313, 331, 337, 349, 367, 373, 379, 397, 401, 409, 419, 421, 431, 433, 439, 443
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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127 is here because 127 - 1 = 126 = 2*63 and 63 is not a prime. 2 is here because 2 - 1 = 1 = 1*2^0 and 1 is not a prime.
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MATHEMATICA
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lofQ[n_]:=Module[{c=Select[Divisors[n-1], OddQ][[-1]]}, !PrimeQ[c]]; Select[ Prime[ Range[100]], lofQ] (* Harvey P. Dale, Jul 24 2021 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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