21986

Appears in sequences

• Number of partitions of n into parts not of the form 23k, 23k+4 or 23k-4. Also number of partitions with at most 3 parts of size 1 and differences between parts at distance 10 are greater than 1.at n=40A035992
• Numbers k such that 2^k - 5 is prime.at n=35A059608
• Numbers n such that sigma(sigma(phi(n))) = sigma(sigma(n)).at n=28A172466
• Triangle read by rows: T(n,k) is the number of 2-compositions of n having k columns in which the top entry is equal to the bottom entry (0<=k<=floor(n/2)).at n=25A181299
• Number of 2-compositions of n having no column with equal entries. A 2-composition of n is a nonnegative matrix with two rows, such that each column has at least one nonzero entry and whose entries sum up to n.at n=9A181301
• G.f. satisfies: A(x) = exp( Sum_{n>=1} x^n/n * Product_{d|n} A(n*x^d/d) ).at n=8A205498
• Numbers that can be approximated in increasing quality by k*k^(1/k).at n=10A291212
• Number of ways to split an integer partition of n into contiguous subsequences with strictly decreasing sums.at n=22A336135