40549

Appears in sequences

• Numbers k such that 6*phi(k) = 5*sigma(k).at n=4A065823
• Triangle read by rows: number of topologies of n nested circles intersecting at most as triples, according to number of factors.at n=58A281350
• G.f.: exp( Sum_{n>=1} sigma_2(n)*sigma_3(n)/sigma(n) * x^n / n ), where sigma_{k}(n) equals the sum of the k-th powers of the divisors of n.at n=9A320416
• a(n) = (1/n) Sum_{k=0..n} Sum_{d|n} phi(d) A241171(n/d, k) for n >= 1, a(0) = 1.at n=5A327026