5181045

Appears in sequences

• Numbers k such that k and k+1 have the same number and sum of divisors.at n=26A054004
• Numbers n such that Product_{d|n} sigma(d) = Product_{d|n+1} sigma(d).at n=21A280087
• Numbers k such that t(k) = t(k+1) where t(k) = tau(k) + sigma(k) = A007503(k) is the number of subgroups of the dihedral group of order 2k.at n=27A322256