Sequences

Sum of n-th powers of divisors of 18.

Sum of n-th powers of divisors of 20.

Sum of n-th powers of divisors of 21.

Sum of n-th powers of divisors of 24.

Sum of n-th powers of divisors of 32.

Sum of n-th powers of divisors of 36.

Sum of n-th powers of divisors of 40.

Sum of n-th powers of divisors of 48.

Sum of n-th powers of divisors of 56.

Duplicate of A020516.

Sum of n-th powers of divisors of 72.

Sum of n-th powers of divisors of 96.

Sum of n-th powers of divisors of 120.

Sum of n-th powers of divisors of 128.

Sum of n-th powers of divisors of 144.

Sum of squares of unitary divisors of n.

Sum of cubes of unitary divisors of n.

Sum of fourth powers of unitary divisors.

Sum of fifth powers of unitary divisors.

Sum of sixth powers of unitary divisors.

Sum of seventh powers of unitary divisors.

Sum of eighth powers of unitary divisors.

Unitary abundant numbers: numbers k such that usigma(k) > 2*k.

If n = p_1^e_1 * ... * p_k^e_k, p_1 < ... < p_k primes, then a(n) = min { p_i^e_i }.

Least possible integer k/(product of digits k) for k with n digits.

a(n) = k, where k/(product of digits of k) is least possible integer for k with n digits.

Related to quintic factorial numbers A008548.

Expansion of (1-25*x)^(-1/5), related to quintic factorial numbers A008548.

a(n) = n-th sextic factorial number divided by 2.

Sum of digits of all the divisors of n.

Euler transform of powers of 2 [1,2,4,8,16,...].

a(n+1) = smallest number that is not the sum of a(n) or fewer terms of a(1),...,a(n).

Smallest k such that k*n+1 is prime.

Smallest prime == 1 (mod n).

Tau_6 (the 6th Piltz divisor function), the number of ordered 6-factorizations of n; Dirichlet convolution of number-of-divisors function (A000005) with A007426.

Dirichlet convolution of primes (A000040) with themselves.

a(1)=1, a(n)= 1 + Sum a(p), p prime, p | n-1.

a(n) is the smallest prime such that a(1), ..., a(n-1) are squares mod a(n).

Largest prime power factor of n.

a(n) = smallest prime == 1 (mod 4) such that a(n) is a square mod a(i), all i<n.

a(n) is the smallest number not of the form a(i) (1<=i<=n-1) or a(i)+a(n-1) (1<=i<=n-2).

a(n+1) is the smallest number not of the form a(i), a(i) + a(n-1), or |a(i) - a(n-1)|.

Numbers of the form binomial(a+b+c, a) + binomial(a+b+c, b) + binomial(a+b+c, c), with a,b,c >= 1.

Largest number that can be made using only the digits of n, exponentiation and concatenation.

Numbers that are sums of consecutive squares.

Numbers which are sums of consecutive triangular numbers.

Numbers that are sums (of a nonempty sequence) of consecutive primes.

Numbers for which the sum of reciprocals of digits is an integer.

Numbers divisible by their last digit.

Positive numbers for which the sum of digits equals the product of digits.