169260domain: NAppears in sequencesExpansion of -1/((1 - x)*(1 - x^2 + 4*x^3)).at n=23A175714Numbers with prime factorization pqrstu^2.at n=21A189985Number of undirected labeled graphs on n+3 nodes with exactly n cycle graphs as connected components.at n=13A215773a(n) = Sum_{k=1..n-1} lcm(lcm(n, k), lcm(n, n-k)).at n=34A338798