22436

Appears in sequences

• a(n) = (2*n+1)*(9*n+1).at n=35A033573
• Numbers k such that sigma(phi(k)) = sigma(k) where sigma is the sum of divisors function A000203 and phi is the Euler totient function A000010.at n=8A033631
• E.g.f.: exp(x+x^2/2)/(1-x).at n=7A130907
• Number of strongly connected directed multigraphs with loops allowed and with n arcs.at n=9A139627
• Numbers n such that sigma(sigma(phi(n))) = sigma(sigma(n)).at n=29A172466
• Number of n X 6 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=13A280438