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A138924
Indices k such that A020505(k)=Phi[k](-6) is prime, where Phi is a cyclotomic polynomial.
2
3, 4, 6, 8, 9, 11, 14, 15, 21, 24, 25, 31, 42, 43, 45, 47, 58, 59, 77, 107, 124, 142, 144, 177, 192, 254, 279, 360, 407, 437, 480, 525, 542, 551, 579, 764, 811, 822, 891, 917, 1018, 1028, 1150, 1326, 1376, 1464, 1468, 1650, 1719, 1924, 2096, 2098, 2176, 2226
OFFSET
1,1
MATHEMATICA
Select[ Range[ 2000], PrimeQ[ Cyclotomic[#, -6]] &] (* Robert G. Wilson v, Mar 25 2012 *)
PROG
(PARI) for( i=1, 999, ispseudoprime( polcyclo(i, -6)) && print1( i", ")) /* use ...subst(polcyclo(i), x, -6)... in PARI < 2.4.2 */
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Apr 03 2008
EXTENSIONS
a(51)-a(54) from Robert Price, Apr 02 2012
STATUS
approved