172011

Appears in sequences

• Numbers whose sum of divisors is a sixth power.at n=33A019424
• Numbers that are a product of distinct Mersenne primes (elements of A000668).at n=20A046528
• Sum of divisors of n, sigma(n) (A000203), is a power of number of divisors of n, d(n) (A000005).at n=13A051281
• Numbers k such that sigma(usigma(k)) is prime.at n=5A063103
• Least k such that sigma(k)=m^n for some m>1.at n=17A063869
• Numbers n such that sigma(n) is a prime power (A025475).at n=21A065523
• m for which p(m) is the least prime dividing #p(n) + 1, i.e., primorial n-th prime augmented by 1 (A005234).at n=24A068488
• Number of nX2 1..4 arrays containing at least one of each value, all equal values connected, rows considered as a single number in nondecreasing order, and columns considered as a single number in increasing order.at n=14A166815
• Positions of records in A175432.at n=14A169981
• 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=18A180162
• Numbers k such that sigma(sigma(k)) is prime.at n=4A247838
• a(n) is the smallest number k such that sigma(k) = 2^n or 0 if no such k exists.at n=18A247956
• 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=16A254352
• Nonprime numbers k such that sum of the divisors of k is a power of 2.at n=14A254603
• Least k such that n divides d(sigma(k)) (d = A000005).at n=18A276043
• Numbers n such that the number of divisors of sum of divisors of n is prime.at n=32A281882
• Sphenic numbers that are the product of Mersenne primes.at n=4A346138
• Irregular table read by rows; the n-th row contains in ascending order the integers m > 1 such that sigma(m) = tau(m)^n; the first row contains 1.at n=9A349838