how can find cyclotomic Polynomial where n=105

Question

question number (D) in picture where n=105

my steps : factor 105 to 3 * 5 * 7 and can't continue to next steps

Answer 1

$$\Phi_{105}(x)= (x-1)^{\mu (105)}(x^{3}-1)^{\mu (35)}(x^{5}-1)^{\mu (21)}(x^{7}-1)^{\mu (15)}(x^{15}-1)^{\mu (7)}(x^{21}-1)^{\mu (5)} (x^{35}-1)^{\mu (3)}(x^{105}-1)^{\mu (1)}$$

$$= (x-1)^{-1}(x^{3}-1)^{1}(x^{5}-1)^{1}(x^{7}-1)^{1}(x^{15}-1)^{-1}(x^{21}-1)^{-1} (x^{35}-1)^{-1}(x^{105}-1)^{1}$$

$$ = {(x^{3}-1)(x^{5}-1)(x^{7}-1)(x^{105}-1) \over (x-1) (x^{15}-1)(x^{21}-1) (x^{35}-1)}=...$$

Answer 2

It's

$\dfrac{(x^{105}-1)(x^3-1)(x^5-1)(x^7-1)}{(x^{15}-1)(x^{21}-1)(x^{35}-1)(x-1)}= x^{48} + x^{47} + x^{46} - x^{43} - x^{42} - 2 x^{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} + $

$x^{12} - x^9 - x^8 - 2 x^7 - x^6 - x^5 + x^2 + x + 1.$

According to Wikipedia,

this cyclotomic polynomial is the first one that has a coefficient other than $1, 0,$ or $−1.$