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A256148 Primitive prime factors of the cyclotomic polynomial sequence Phi(3, k) (or Phi(6, k)) in the order in which they occur. 4
3, 7, 13, 31, 43, 19, 73, 37, 157, 61, 211, 241, 307, 127, 421, 463, 79, 601, 757, 271, 67, 331, 151, 1123, 397, 97, 1483, 223, 547, 1723, 139, 631, 283, 109, 103, 181, 2551, 379, 919, 409, 2971, 3307, 163, 3541, 523, 3907, 613, 4423, 4831, 1657, 5113, 751 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Phi(3,k) = k^2 + k + 1 and Phi(6,k) = k^2 - k + 1.
Interesting scatter plot.
The terms correspond to the new primes of A081257 in the order of their appearance for n>1 and when A081257(m)>m. - Bill McEachen, Oct 13 2022
LINKS
MATHEMATICA
prim = {}; Do[prim = Join[prim, Complement[First /@ FactorInteger[Cyclotomic[6, k]], prim]], {k, 1000}]; prim
PROG
(PARI) lista(nn) = {vs = []; for (n=1, nn, vp = factor(polcyclo(6, n))[, 1]; for (i=1, #vp, if (!vecsearch(vs, vp[i]), print1(vp[i], ", "); vs = vecsort(concat(vs, vp[i]), , 8); ); ); ); } \\ Michel Marcus, Mar 20 2015
CROSSREFS
Sequence in context: A117708 A093431 A243765 * A083520 A336801 A162869
KEYWORD
nonn,look
AUTHOR
Robert Price, Mar 16 2015
STATUS
approved

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Last modified March 28 10:55 EDT 2024. Contains 371241 sequences. (Running on oeis4.)