A219278 Numbers n such that ChebyshevT[16,n] is prime.

2, 13, 20, 21, 33, 74, 87, 88, 94, 104, 105, 127, 172, 182, 185, 188, 215, 224, 233, 240, 249, 258, 278, 281, 292, 293, 304, 329, 337, 365, 399, 416, 433, 440, 468, 471, 489, 502, 509, 529, 540, 573, 576, 583, 608, 612, 615, 622, 630, 631, 639, 685, 689, 707

Offset: 1

Author

Michel Lagneau, Nov 17 2012

Keywords

• nonn

Comments

ChebyshevT[16,x] is the 16th Chebyshev polynomial of the first kind evaluated at x.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A144131, A144132, A219276, A219277.

Programs

Maple

P:= unapply(orthopoly[T](16,x),x):
select(isprime @ P, [$1..1000]); # Robert Israel, Aug 13 2018

Mathematica

lst={}; Do[If[PrimeQ[ChebyshevT [16, n]], AppendTo[lst, n]], {n, 10^3}]; lst
Select[Range[800],PrimeQ[ChebyshevT[16,#]]&] (* Harvey P. Dale, Jan 23 2016 *)

PARI

is(n)=ispseudoprime(polchebyshev(16,1,n)) \\ Charles R Greathouse IV, May 22 2017