51089domain: NAppears in sequencesG.f.: 1/((1-x)*(1-x^2)*(1-x^3)*(1-x^4)*(1-x^5))^2.at n=26A117487Semiprimes of the form (2^k - m)*(m*2^k - 1).at n=20A239038a(n) = Sum_{j=1..n*(n-1)} (n*j mod (n+j)).at n=19A309341Number of compositions of n with circular differences all equal to 1, 0, or -1.at n=21A325591