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A138925 Indices k such that A020504(k)=Phi[k](-5) is prime, where Phi is a cyclotomic polynomial. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 2 22:46 EST 2021. Contains 349445 sequences. (Running on oeis4.)