The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A262405 Least k such that the k-th cyclotomic polynomial has -n as a coefficient. 5
 4, 1, 105, 385, 1365, 2145, 2805, 3135, 6545, 7917, 10465, 10465, 10465, 10465, 10465, 11305, 11305, 11305, 11305, 11305, 11305, 11305, 15015, 17255, 17255, 17255, 20615, 25935, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Suzuki proves that a(n) exists for each n. LINKS Jiro Suzuki, On coefficients of cyclotomic polynomials, Proc. Japan Acad. Ser. A Math. Sci. 63:7 (1987), pp. 279-280. R. C. Vaughan, Bounds for the coefficients of cyclotomic polynomials, Michigan Math. J. 21 (1974), 289-295 (1975). EXAMPLE Phi(105) = x^48 + x^47 + x^46 - x^43 - x^42 - 2x^41 - x^40 - x^39 + x^36 + x^35 + x^34 + x^33 + x^32 + x^31 - x^28 - x^26 - x^24 - x^22 - x^20 + x^17 + x^16 + x^15 + x^14 + x^13 + x^12 - x^9 - x^8 - 2x^7 - x^6 - x^5 + x^2 + x + 1, with -2 as the coefficient of x^7 (among others), and this is the least k for which -2 appears, so a(2) = 105. MATHEMATICA Table[k = 1; While[! MemberQ[CoefficientList[Cyclotomic[k, x], x], -n], k++]; k, {n, 0, 9}] (* Michael De Vlieger, Sep 29 2015 *) PROG (PARI) a(n)=my(k, v); while(!setsearch(Set(Vec(polcyclo(k++))), -n), ); k CROSSREFS Cf. A013594, A013595, A046887, A262404, A160340, A278567. Sequence in context: A299582 A211341 A280620 * A152841 A125083 A094423 Adjacent sequences:  A262402 A262403 A262404 * A262406 A262407 A262408 KEYWORD nonn AUTHOR Charles R Greathouse IV, Sep 21 2015 EXTENSIONS More terms from Seiichi Manyama, Dec 22 2018 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified July 25 16:03 EDT 2021. Contains 346291 sequences. (Running on oeis4.)