34404domain: NAppears in sequencesa(n) = (7*n+1)*(7*n+6).at n=26A001526Number of n-permutations with at least one cycle of length >=4.at n=8A202364a(n) = 3*(9*n - 1)*(3*n - 2).at n=21A277985a(n) = Sum_{k=1..n} binomial(2*n, n-k) * phi(k), where phi is the Euler totient function.at n=7A356340