A258357 Numbers n such that cyclotomic polynomial value Phi(7,n!) is prime.

0, 1, 2, 3, 13, 470, 2957

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: A270314 A132484 A376060 * A160858 A062648 A094003

Adjacent sequences: A258354 A258355 A258356 * A258358 A258359 A258360

Keyword

nonn,more

Author

Robert Price, May 27 2015

Status

approved