A138924 Indices k such that A020505(k)=Phi[k](-6) is prime, where Phi is a cyclotomic polynomial.

3, 4, 6, 8, 9, 11, 14, 15, 21, 24, 25, 31, 42, 43, 45, 47, 58, 59, 77, 107, 124, 142, 144, 177, 192, 254, 279, 360, 407, 437, 480, 525, 542, 551, 579, 764, 811, 822, 891, 917, 1018, 1028, 1150, 1326, 1376, 1464, 1468, 1650, 1719, 1924, 2096, 2098, 2176, 2226

Offset: 1

Author

M. F. Hasler, Apr 03 2008

Keywords

• nonn

Links

• Robert Price, Table of n, a(n) for n = 1..104
• Yves Gallot, Cyclotomic polynomials and prime numbers

Crossrefs

Cf. A020505, A138920-A138940.

Programs

Mathematica

Select[ Range[ 2000], PrimeQ[ Cyclotomic[#, -6]] &] (* Robert G. Wilson v, Mar 25 2012 *)

PARI

for( i=1,999, ispseudoprime( polcyclo(i,-6)) && print1( i",")) /* use ...subst(polcyclo(i),x,-6)... in PARI < 2.4.2 */

Extensions

a(51)-a(54) from Robert Price, Apr 02 2012