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

Author

Arkadiusz Wesolowski, Jul 16 2015

Keywords

• nonn
• more

Comments

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

Links

• Wikipedia, Covering set

Crossrefs

Cf. A019434, A046800.

Programs

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