200970

Appears in sequences

• Numbers k such that k | sigma_3(k) - phi(k)^3.at n=35A055697
• Smallest number beginning with 2 and having exactly n distinct prime divisors.at n=5A077327
• G.f. is the polynomial (Product_{k=1..28} (1 - x^(3*k)))/(1-x)^28.at n=5A162727
• Numbers with prime factorization pqrstu^2.at n=29A189985
• Number of n X 4 0..1 arrays avoiding 0 0 1 and 1 0 0 horizontally and 0 0 1 and 1 0 1 vertically.at n=27A209646
• Let s(k) denote the sum of the even proper divisors of k. The sequence lists the pairs of numbers (x, y) such that s(x) = y and s(y) = x.at n=26A279812
• List of ordered pairs (x, y) from A279812.at n=26A279950
• a(n) = n*(2*n+1)*binomial(n+2,n)/3.at n=27A289643
• Number of labeled simple graphs with n edges covering n vertices such that it is not possible to choose a different vertex from each edge (non-choosable).at n=8A369144