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A214455 Number of primes of the form x^16 + 1 less than 10^n. 5
1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6, 6, 6, 9, 11, 11, 12, 14, 17, 20, 26, 27, 30, 34, 42, 49, 53, 59, 64, 68, 80, 93, 101, 111, 129, 147, 169, 187, 212, 235, 264, 292, 329, 386, 427, 483, 544, 622 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

It is conjectured that there are infinitely many primes of the form x^16 + 1 (and thus this sequence never becomes constant), but this has not been proved.

LINKS

Table of n, a(n) for n=1..70.

EXAMPLE

a(26) = 2 because the only primes or the form x^16 + 1 < 10^26 are the primes: 2, 65537.

PROG

(PARI) a(n) = sum(k=1, (10^n-1)^(1/16), isprime(k^16+1))

CROSSREFS

Cf. A083844, A214452, A214454.

Sequence in context: A069926 A077429 A204553 * A060417 A097944 A037203

Adjacent sequences:  A214452 A214453 A214454 * A214456 A214457 A214458

KEYWORD

nonn

AUTHOR

Henryk Dabrowski, Jul 18 2012

STATUS

approved

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Last modified January 17 16:47 EST 2018. Contains 297822 sequences.