A138935 - OEIS

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A138935

Indices k such that A019323(k)=Phi[k](5) is prime, where Phi is a cyclotomic polynomial.

3

3, 7, 10, 11, 12, 13, 24, 28, 47, 48, 49, 56, 57, 88, 90, 92, 108, 110, 116, 120, 127, 134, 141, 149, 161, 181, 198, 202, 206, 236, 248, 288, 357, 384, 420, 458, 500, 530, 536, 619, 620, 694, 798, 897, 929, 981, 992, 1064, 1134, 1230, 1670, 1807, 2094, 2369

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OFFSET

1,1

COMMENTS

Can there be an odd multiple of 5 in this sequence?

LINKS

Robert Price, Table of n, a(n) for n = 1..110

Yves Gallot, Cyclotomic polynomials and prime numbers

Index entries for cyclotomic polynomials, values at X

MATHEMATICA

Select[Range[1000], PrimeQ[Cyclotomic[#, 5]] &]

PROG

(PARI) for( i=1, 999, ispseudoprime( polcyclo(i, 5)) && print1( i", "))

CROSSREFS

Cf. A019323, A138920-A138940.

Sequence in context: A144385 A144399 A310176 * A375474 A030325 A095947

Adjacent sequences: A138932 A138933 A138934 * A138936 A138937 A138938

KEYWORD

nonn

AUTHOR

M. F. Hasler, Apr 03 2008

EXTENSIONS

a(48)-a(54) from Robert Price, Apr 14 2012

STATUS

approved