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A161504 Primes congruent to {1, 2, 10, 11, 19, 20} mod 21. 1
2, 11, 19, 23, 31, 41, 43, 53, 61, 73, 83, 103, 107, 127, 137, 149, 157, 167, 179, 191, 199, 211, 229, 233, 241, 251, 263, 271, 283, 293, 313, 317, 337, 347, 359, 367, 379, 389, 397, 401, 409, 419, 421, 431, 439, 443, 461, 463, 503, 523, 547, 557, 569, 577, 587 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The cyclotomic polynomial Phi(21p,x) is flat only for p in this sequence.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1001 [a(1)=2 inserted by Georg Fischer, Jul 26 2020]
FORMULA
MATHEMATICA
Flatten[Table[Select[21*n+{-10, -2, -1, 1, 2, 10}, PrimeQ], {n, 50}]]
Select[Prime[Range[2, 250]], MemberQ[{1, 2, 10, 11, 19, 20}, Mod[#, 21]]&] (* Harvey P. Dale, May 03 2019 *)
CROSSREFS
Sequence in context: A023173 A018443 A163058 * A079062 A038930 A019375
KEYWORD
nonn
AUTHOR
T. D. Noe, Jun 17 2009
EXTENSIONS
a(1)=2 inserted by Georg Fischer, Jul 26 2020
STATUS
approved

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Last modified March 28 11:57 EDT 2024. Contains 371241 sequences. (Running on oeis4.)