A257861 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.

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

Offset

1,1

Comments

For every n there exists a Sierpiński/Riesel number with modulus a(n).

Links

Table of n, a(n) for n=1..28.

Wikipedia, Covering set

Prog

(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

Crossrefs

Cf. A019434, A046800.

Sequence in context: A338853 A343797 A292354 * A050497 A162282 A008606

Adjacent sequences: A257858 A257859 A257860 * A257862 A257863 A257864

Keyword

nonn,more

Author

Arkadiusz Wesolowski, Jul 16 2015

Status

approved