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

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

Offset: 1

Author

Robert Price, May 27 2015

Keywords

• nonn
• more

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

Examples

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

Crossrefs

Cf. A002981, A002982, A046029, A200906.

Programs

Mathematica

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