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A275528
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Prime factors of numbers of the form 4^(2^m) - 2^(2^m) + 1 with m >= 0.
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3
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3, 13, 97, 193, 241, 673, 769, 12289, 786433, 22253377, 39714817, 152371201, 597688321, 1107296257, 3221225473, 7348420609, 11560943617, 29796335617, 74490839041, 77309411329, 206158430209, 246423748609, 448203325441, 2422022479873, 5469640851457, 28114855919617
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OFFSET
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1,1
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COMMENTS
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Primes p other than 3 such that one third of the multiplicative order of 2 (mod p) is a power of 2.
Primes in A255772 (except 7), sorted.
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LINKS
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EXAMPLE
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3 divides 2^2 - 2^1 + 1 = 3.
13 divides 2^4 - 2^2 + 1 = 13.
97 divides 2^16 - 2^8 + 1 = 65281.
193 divides 2^32 - 2^16 + 1 = 4294901761.
241 divides 2^8 - 2^4 + 1 = 241.
673 divides 2^16 - 2^8 + 1 = 65281.
769 divides 2^128 - 2^64 + 1 = 340282366920938463444927863358058659841.
12289 divides 2^2048 - 2^1024 + 1.
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PROG
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(PARI) forprime(p=3, 10^15, o=znorder(Mod(2, p))/3; x=ispower(2*o); if(p==3||2^(x-1)==o, print1(p, ", ")));
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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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