23806

Appears in sequences

• Becomes prime or 4 after exactly 9 iterations of f(x) = sum of prime factors of x.at n=17A048131
• Centered 23-gonal numbers.at n=45A069174
• Number of -3..3 arrays x(i) of n+1 elements i=1..n+1 with x(i)+x(j), x(i+1)+x(j+1), -(x(i)+x(j+1)), and -(x(i+1)+x(j)) having two or three distinct values for every i<=n and j<=n.at n=8A211500
• Semiprimes of the form 5*n^2 + 1.at n=23A212707
• Numbers n such that Q(sqrt(n)) has class number 9.at n=37A218041
• L.g.f.: -log(1 - Sum_{n>=1} x^(n*(n+1)/2)) = Sum_{n>=1} a(n)*x^n/n.at n=22A224678
• Number of partitions p of n such that median(p) <= multiplicity(min(p)).at n=40A240213
• Smallest number x such that sigma(x) = sigma(x(n)), where x(n) is the n-th arithmetic derivatives of x and x is not equal to x(n).at n=12A246774