210035

Appears in sequences

• a(n) = n*(n + 1)*(n^2 - 3*n + 5)/6.at n=34A006484
• Number of numbers up to 10^n that are products of two primes.at n=5A036352
• a(n) = number of semiprimes < 10^n.at n=6A066265
• Triangle read by rows: T(k,n) is number of numbers <= 10^n that are products of k primes.at n=48A126280
• Number of semiprimes among n-th million natural numbers.at n=0A216593
• Triangle read by rows: T(n, k) = Sum_{d=0..n-k} binomial(n, d)*StirlingS2(n-d, k)*8^(n-d-k), with 0 <= k <= n.at n=32A364071