A215701 Number of primes of the form 1 + b^2048 for 1 < b < 10^n.

0, 0, 1, 4, 40, 276

Offset

1,4

Comments

Primes 1 + b^2048 are a form of generalized Fermat primes.

It is conjectured that a(n) is asymptotic to 0.00352764*li(10^n)

Links

Table of n, a(n) for n=1..6.

Yves Gallot, Status of the smallest base values yielding Generalized Fermat primes

Yves Gallot, How many prime numbers appear in a sequence ?

Yves Gallot, A Problem on the Conjecture Concerning the Distribution of Generalized Fermat Prime numbers (a new method for the search for large primes)

Example

a(4) = 4 because the generalized Fermat numbers F_11(b) where b<10^4 are prime only for b = 150, 2558, 4650, 4772.

Prog

(PARI) a(n) = sum(b=1, 10^n/2-1, isprime((2*b)^2048+1))

Crossrefs

Cf. A215047, A215048, A215049, A215050, A215051, A215057, A215058, A215698.

Sequence in context: A119635 A367557 A283660 * A366667 A212699 A061318

Adjacent sequences: A215698 A215699 A215700 * A215702 A215703 A215704

Keyword

nonn

Author

Henryk Dabrowski, Aug 21 2012

Status

approved