A138923 Indices k such that A020506(k)=Phi[k](-7) is prime, where Phi is a cyclotomic polynomial.
3, 9, 10, 15, 17, 23, 25, 26, 27, 28, 29, 36, 42, 47, 48, 61, 76, 84, 110, 126, 148, 210, 224, 262, 280, 288, 296, 298, 325, 327, 332, 352, 365, 456, 513, 528, 740, 1062, 1162, 1445, 1460, 1518, 1619, 1660, 2094, 2130, 2260, 2380, 3398, 3447, 3918
Offset: 1
Keywords
Links
- Robert Price, Table of n, a(n) for n = 1..97
- Yves Gallot, Cyclotomic polynomials and prime numbers
Programs
-
Mathematica
Select[ Range[ 2400], PrimeQ[ Cyclotomic[#, -7]] &] (* Robert G. Wilson v, Mar 25 2012 *)
-
PARI
for( i=1,999, ispseudoprime( polcyclo(i,-7)) && print1( i",")) /* use ...subst(polcyclo(i),x,-7)... in PARI < 2.4.2 */
Comments