2113665

Appears in sequences

• a(n) = sigma_7(n), the sum of the 7th powers of the divisors of n.at n=7A013955
• Numerator of sum of -7th powers of divisors of n.at n=7A017677
• Sum of n-th powers of divisors of 8.at n=7A034496
• Sum of (n-1)-th powers of divisors of n.at n=7A082245
• Triangular array, read by rows: T(n,k) = Sum_{d|n} d^k, 0 <= k < n.at n=35A082771
• Pseudoprimes (base-2) equal to the product of 5 primes not necessarily distinct.at n=3A112443
• Number of cases in which the first player gets killed in a Russian roulette game when 7 players use a gun with n chambers and the number of the bullets can be from 1 to n. In the game they do not rotate the cylinder after the game starts.at n=21A117302
• Fermat pseudoprimes to base 2 divisible by 15.at n=15A216364
• Pseudoprimes to a twin prime criterion of Aebi and Cairns.at n=31A224695
• Pseudoprimes n to base 2 such that n+2 and n+4 are primes.at n=3A230489
• Smallest sets of 3 consecutive odd numbers that are primes or pseudoprimes (base 2). The initial odd number is listed.at n=17A230808
• Poulet numbers (Fermat pseudoprimes to base 2) with a record number of divisors that are also Poulet numbers.at n=4A300327
• Poulet numbers (Fermat pseudoprimes to base 2) k that have an abundancy index sigma(k)/k that is larger than the abundancy index of all smaller Poulet numbers.at n=4A328691
• Fermat pseudoprimes to base 2 that are palindromic in base 2.at n=17A346567
• Array T(n,m) = (2^(n*m)-1)/(2^m-1) read by antidiagonals, n,m>=1.at n=48A360965
• Base-2 Fermat pseudoprimes k such that (k-1)/ord(2, k) > (m-1)/ord(2, m) for all base-2 Fermat pseudoprimes m < k, where ord(2, k) is the multiplicative order of 2 modulo k.at n=21A367319
• a(n) is the smallest number m with n divisors d such that d^m mod m = d.at n=21A371513
• a(n) is the least k that has exactly n proper divisors d such that (-d)^k == -d (mod k).at n=21A380393