A138919 Indices k such that A020510(k)=Phi[k](-11) is prime, where Phi is a cyclotomic polynomial.

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

Author

M. F. Hasler, Apr 04 2008

Keywords

• nonn

Comments

Larger values are probable primes.

Links

• Robert Price, Table of n, a(n) for n = 1..91
• Yves Gallot, Cyclotomic polynomials and prime numbers
• Index entries for cyclotomic polynomials, values at X

Crossrefs

Cf. A020510, A138920-A138940, A070518-A070527.

Programs

Mathematica

Select[Range[1000], PrimeQ[Cyclotomic[#, -11]] &]

PARI

for( i=1,999, ispseudoprime( polcyclo(i,-11)) & print1(",",i)) /* use ...subst(polcyclo(i),x,-11)... in PARI < 2.4.2 */

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