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A258357 Numbers n such that cyclotomic polynomial value Phi(7,n!) is prime. 1
0, 1, 2, 3, 13, 470, 2957 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Except for the values 0,1,2 and 3, terms correspond to probable primes.

a(8) > 6502.

Also, numbers n such that n! belongs to A100330. - Michel Marcus, May 30 2015

LINKS

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

EXAMPLE

3 is in the sequence because Phi(7,3!) = 1 + 6 + 6^2 + 6^3 + 6^4 + 6^5 + 6^6 = 55987 is prime.

MATHEMATICA

Select[Range[0, 6502], PrimeQ[Cyclotomic[7, #!]] &]

CROSSREFS

Cf. A002981, A002982, A046029, A200906.

Sequence in context: A090100 A270314 A132484 * A160858 A062648 A094003

Adjacent sequences:  A258354 A258355 A258356 * A258358 A258359 A258360

KEYWORD

nonn,more

AUTHOR

Robert Price, May 27 2015

STATUS

approved

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Last modified May 6 18:38 EDT 2021. Contains 343586 sequences. (Running on oeis4.)