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A257861
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Numbers n such that d(m) - f(m) >= n/2^f(m), where m = 2^n - 1, d(m) is the number of distinct prime factors of m, and f(m) is the number of Fermat primes less than or equal to 65537 that divide m.
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2
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24, 48, 64, 72, 80, 96, 112, 128, 144, 160, 192, 224, 240, 288, 320, 336, 352, 384, 416, 448, 480, 576, 672, 800, 864, 960, 1056, 1440
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OFFSET
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1,1
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COMMENTS
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For every n there exists a Sierpiński/Riesel number with modulus a(n).
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LINKS
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PROG
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(PARI) lista(nn) = {vfp = [3, 5, 17, 257, 65537]; for(n = 1, nn, m = 2^n-1; dm = omega(m); fm = sum(k=1, #vfp, (m % vfp[k]) == 0); if (dm - fm >= n/2^fm, print1(n, ", ")); ); } \\ Michel Marcus, Jul 20 2015
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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