199753347

Appears in sequences

• Least k such that sigma(k)=m^n for some m>1.at n=27A063869
• Positions of records in A175432.at n=24A169981
• a(n) is the smallest number N such that sigma(N) is an n-th power but not a higher power, with a(n) = 0 if no such number exists.at n=28A180162
• a(n) is the smallest number k such that sigma(k) = 2^n or 0 if no such k exists.at n=28A247956
• a(n) is the least composite x such that sigma(x) divides (x-1)^n but not (x-1)^(n-1), for n >= 2.at n=26A254352
• Least k such that n divides d(sigma(k)) (d = A000005).at n=28A276043
• Sphenic numbers that are the product of Mersenne primes.at n=18A346138