A200906 Numbers n such that cyclotomic polynomial value Phi(5,n!) is prime.

0, 1, 2, 4, 5, 21, 44, 64, 244, 268, 2415

Offset: 1

Author

Serge Batalov, Nov 23 2011

Keywords

• nonn

Comments

2415 corresponds to a probable prime. - Serge Batalov, Nov 24 2011

a(12) > 15000. - Robert Price, Jun 20 2015

Examples

			5 is in the sequence because Phi(5,5!) = ((5!)^5-1)/(5!-1)= 209102521 is prime.
		

Crossrefs

Cf. A002981, A002982, A046029, A046029.

Programs

Mathematica

Do[If[PrimeQ[Cyclotomic[5, n!]], Print[n]], {n, 0, 600}]

PARI

for(n=0,600,x=n!;if(isprime(eval(polcyclo(5))),print(n)))