A138922 Indices k such that A020507(k)=Phi[k](-8) is prime, where Phi is a cyclotomic polynomial.

6, 15, 18, 21, 39, 69, 159, 165, 174, 231, 378, 408, 501, 504, 606, 873, 897, 1122, 1209, 1395, 1947, 2040, 2361, 2778, 3369, 7305, 7647, 8154, 8331, 9483, 13071, 14616, 15819, 20301, 21282, 27144, 31083, 34725, 35775, 36855, 38118, 39360

Offset: 1

Author

M. F. Hasler, Apr 03 2008

Keywords

• nonn
• more

Links

• Yves Gallot, Cyclotomic polynomials and prime numbers

Crossrefs

Cf. A020507, A138920-A138940.

Programs

Mathematica

Select[Range[1000], PrimeQ[Cyclotomic[#, -8]] &]

PARI

for( i=1,999, ispseudoprime( polcyclo(i,-8)) && print1( i",")) /* use ...subst(polcyclo(i),x,-8)... in PARI < 2.4.2 */

Extensions

a(18)-a(42) from Robert Price, Mar 25 2012