A138938 - OEIS

A138938

Indices k such that A019326(k)=Phi[k](8) is prime, where Phi is a cyclotomic polynomial.

1, 3, 9, 30, 42, 78, 87, 138, 189, 303, 318, 330, 408, 462, 504, 561, 1002, 1389, 1746, 1794, 2040, 2418, 2790, 3894, 4077, 4722, 6738, 10641, 14610, 14616, 15294, 16662, 18966, 19059, 26142, 27144, 28299, 31638, 33639, 39360

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..40.

Yves Gallot, Cyclotomic polynomials and prime numbers

Index entries for cyclotomic polynomials, values at X

MATHEMATICA

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

PROG

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

CROSSREFS

Cf. A019326, A138920-A138940.

Sequence in context: A007472 A292756 A151451 * A154147 A179545 A163129

Adjacent sequences: A138935 A138936 A138937 * A138939 A138940 A138941

KEYWORD

nonn

AUTHOR

M. F. Hasler, Apr 03 2008

EXTENSIONS

a(17)-a(40) from Robert Price, Apr 20 2012

STATUS

approved