n(2n-1)(2n+1) habis dibagi 3

u/ n = 1
3 = 1(2-1)(2+1)
3 = 3

u/ n = k
k(2k-1)(2k+1) = 3 (kalo g salah ingat)

u/ n = k + 1
cari sendiri hehe
smg membantu