A138925 Indices k such that A020504(k)=Phi[k](-5) is prime, where Phi is a cyclotomic polynomial.

5, 6, 12, 14, 22, 24, 26, 28, 45, 48, 55, 56, 67, 88, 92, 94, 98, 99, 101, 103, 108, 114, 116, 120, 229, 236, 248, 254, 265, 282, 288, 298, 322, 347, 362, 384, 399, 420, 500, 536, 567, 615, 620, 714, 835, 992, 1047, 1064, 1238, 1794, 1858, 1962, 2313, 2397

Offset

1,1

Links

Robert Price, Table of n, a(n) for n = 1..114

Yves Gallot, Cyclotomic polynomials and prime numbers

Mathematica

Select[ Range[ 2000], PrimeQ[ Cyclotomic[#, -5]] &] (* Robert G. Wilson v, Mar 25 2012 *)

Prog

(PARI) for( i=1, 999, ispseudoprime( polcyclo(i, -5)) && print1( i", ")) /* use ...subst(polcyclo(i), x, -5)... in PARI < 2.4.2 */

Crossrefs

Cf. A020504, A138920-A138940.

Sequence in context: A047319 A244368 A185031 * A088767 A032707 A240756

Adjacent sequences: A138922 A138923 A138924 * A138926 A138927 A138928

Keyword

nonn

Author

M. F. Hasler, Apr 03 2008

Extensions

a(53)-a(54) from Robert Price, Apr 05 2012

Status

approved