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A215962 Number of primes of the form 1 + b^16384 for 1 < b < 10^n. 0
0, 0, 0, 0, 1, 33, 137 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

Primes 1 + b^16384 are a form of generalized Fermat primes.

It is conjectured that a(n) is asymptotic to 0.000488872*li(10^n)

LINKS

Table of n, a(n) for n=1..7.

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)

Mersenne Wiki, Table of known GF primes b^n+1 where n (exponent) is at least 8192

EXAMPLE

a(5) = 1 because the generalized Fermat numbers F_14(b) where b<10^5 are prime only for b = 67234.

PROG

(PARI) a(n) = sum(b=1, 10^n/2-1, isprime((2*b)^16384+1))

CROSSREFS

Cf. A215047, A215048, A215049, A215050, A215051, A215057, A215058, A215698, A215699, A215700.

Sequence in context: A158588 A232538 A231758 * A084028 A283552 A007260

Adjacent sequences:  A215959 A215960 A215961 * A215963 A215964 A215965

KEYWORD

nonn

AUTHOR

Henryk Dabrowski, Aug 29 2012

STATUS

approved

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Last modified August 4 21:32 EDT 2021. Contains 346455 sequences. (Running on oeis4.)