A230798 - OEIS

A230798

The number of distinct coefficients in the n-th cyclotomic polynomial.

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

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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