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

1,1

Links

Robert Price, Table of n, a(n) for n = 1..104

Yves Gallot, Cyclotomic polynomials and prime numbers

Mathematica

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

Prog

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

Crossrefs

Cf. A020505, A138920-A138940.

Sequence in context: A138097 A193732 A000592 * A188015 A192284 A024324

Adjacent sequences: A138921 A138922 A138923 * A138925 A138926 A138927

Keyword

nonn

Author

M. F. Hasler, Apr 03 2008

Extensions

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

Status

approved