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A230798 The number of distinct coefficients in the n-th cyclotomic polynomial. 3
2, 1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 3, 1, 2, 3, 2, 1, 3, 1, 3, 3, 2, 1, 3, 2, 2, 2, 3, 1, 3, 1, 2, 3, 2, 3, 3, 1, 2, 3, 3, 1, 3, 1, 3, 3, 2, 1, 3, 2, 3, 3, 3, 1, 3, 3, 3, 3, 2, 1, 3, 1, 2, 3, 2, 3, 3, 1, 3, 3, 3, 1, 3, 1, 2, 3, 3, 3, 3, 1, 3, 2, 2, 1, 3, 3, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) = 1 if n is a prime.

The sum of the coefficients in the n-th cyclotomic polynomial is given by A020500.

The first occurrence of 4 in this sequence is a(105).

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

EXAMPLE

a(12)=3 because the distinct coefficients of the 12th cyclotomic polynomial, x^4-x^2+1, are 0, 1 and -1.

MATHEMATICA

Table[Length[Union[CoefficientList[Cyclotomic[n, x], x]]], {n, 100}] (* T. D. Noe, Dec 09 2013 *)

PROG

(PARI) a(n) = #vecsort(Vec(polcyclo(n)), , 8)

CROSSREFS

Cf. A020500, A230799.

Cf. A231611 (least k for which cyclotomic(k) has n distinct terms).

Sequence in context: A053574 A321944 A065203 * A266224 A029396 A084746

Adjacent sequences:  A230795 A230796 A230797 * A230799 A230800 A230801

KEYWORD

nonn

AUTHOR

Colin Barker, Oct 30 2013

STATUS

approved

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Last modified April 26 12:00 EDT 2019. Contains 322472 sequences. (Running on oeis4.)