67191

Appears in sequences

• a(n) = T(n, 2*n-7), T given by A027960.at n=14A027969
• Expansion of g.f.: (1-5*x)/((1-6*x)*(1-x)^2).at n=7A094259
• Take a squarefree semiprime and take the difference of its prime factors. If it is a squarefree semiprime repeat the process. Sequence lists the squarefree semiprimes that generate other squarefree semiprimes only in the first k steps of this process. Case k = 5.at n=29A296812
• a(n) = Sum_{1 <= i <= j <= k <= m <= n} gcd(i,j,k,m).at n=32A344992