19358

Appears in sequences

• Numbers k such that k and k+1 have same sum of divisors.at n=11A002961
• Numbers k such that k and k+1 have the same sum but an unequal number of divisors.at n=7A054007
• Numbers k such that sigma(k) divides sigma(k+1), where sigma(k) is sum of positive divisors of k.at n=23A058072
• Numbers k such that sigma(k+1) divides sigma(k), where sigma(k) is the sum of positive divisors of k.at n=27A058073
• Numbers k such that sigma(k)*omega(k) = sigma(k+1)*omega(k+1), where omega(k) is the number of distinct prime divisors of n (A001221).at n=7A063071
• Numbers k such that gcd(sigma(k), sigma(k+1)) > k.at n=38A066025
• G.f. satisfies: A(x) = Sum_{n>=0} x^n*[Sum_{k=0..n} C(n,k)^2 *x^k* A(x)^k].at n=10A181665
• G.f. satisfies A(x) = (1 + x*A(x)) * (1 + x*A(x)^5).at n=5A215624
• Number of binary arrays indicating the locations of trailing edge maxima of a random length-n 0..2 array extended with zeros and convolved with 1,2,1.at n=21A222121
• Numbers n such that sigma(n+1) - sigma(n) = k*n for some integer k, where sigma(n) = A000203 (sum of divisors of n).at n=19A223136
• Table of consecutive numbers with the same sum of divisors.at n=22A225757
• Numbers k such that the coefficient of x^k in the expansion of Product_{m >= 1} (1-x^m)^15 is zero.at n=9A322043
• Numbers m such that the delta(m) = abs(sigma(m+1)/(m+1) - sigma(m)/(m)) is smaller than delta(k) for all k < m.at n=18A335071
• Numbers k such that sum of distinct primes dividing k is equal to the sum of proper divisors of k+1.at n=8A354603
• a(n) = (2*n^3 - n^2 + 3*n - 2)/2.at n=26A363288