>>75(1), 78

円分多項式Φ_d(x)を使うと、x^n -1 = Π[d|n] Φ_d(x),

Φ_1(x) = x-1,
Φ_d(x) = Π[0<k<d, (k,d)=1] {x-(ω_d)^k}, ω_d = exp(2πi/d).

http://mathworld.wolfram.com/CyclotomicPolynomial.html
http://www.kaynet.or.jp/~kay/misc/cyclotomic.html (1≦n≦30)
http://www.akanekodou.sytes.net/math/pdf/cyclotomic.pdf (1≦n≦80)
http://www.math.h.kyoto-u.ac.jp/~yamasaki/a3c.html (n=65,104,105,112,130,140,144,156,168,180,210)