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URL: https://oeis.org/A138919

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A138919
Indices k such that A020510(k)=Phi[k](-11) is prime, where Phi is a cyclotomic polynomial.
3
5, 7, 18, 20, 21, 30, 34, 36, 38, 52, 54, 60, 90, 104, 117, 123, 146, 159, 179, 182, 229, 278, 388, 405, 410, 439, 552, 557, 735, 806, 807, 1220, 1272, 1568, 1688, 1696, 1710, 1814, 2136, 2262, 2288, 2862, 3679, 3814, 4058, 4304, 4480, 5070, 5136, 5154
OFFSET
1,1
COMMENTS
Larger values are probable primes.
MATHEMATICA
Select[Range[1000], PrimeQ[Cyclotomic[#, -11]] &]
PROG
(PARI) for( i=1, 999, ispseudoprime( polcyclo(i, -11)) & print1(", ", i)) /* use ...subst(polcyclo(i), x, -11)... in PARI < 2.4.2 */
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Apr 04 2008
EXTENSIONS
Edited by T. D. Noe, Oct 30 2008
a(32)-a(44) from Robert Price, Mar 16 2012
a(45)-a(50) from Robert Price, Apr 14 2012
STATUS
approved