2016/11/10 by Tóth, László
#11A25 #11Y70 #20K01 #20K27 #Combinatorics (math.CO) #FOS: Mathematics #Group Theory (math.GR) #Number Theory (math.NT)
paper · doi:10.48550/arxiv.1611.03302
We deduce direct formulas for the total number of subgroups and the number of subgroups of a given order of the group ℤm× ℤn × ℤr × ℤs, where m,n,r,s∈ ℕ. The proofs are by some simple group theoretical and number theoretical arguments based on Goursat's lemma for groups. Two conjectures are also formulated.