218520

Appears in sequences

• a(n) = number of permutations of (1,2,...,n) producible by an ordered triple of distinct transpositions.at n=13A253171
• Numbers k such that (sigma(k) + sigma(k + sigma(k))) / k is an integer where sigma(k) = A000203(k) is the sum of the divisors of k.at n=28A383392