60931

Appears in sequences

• Number of quadruples [i,j,k,l] with all entries between 1 and n such that gcd(i,j) = gcd(k,l).at n=18A124162
• G.f.: Product_{k>=1} (1 + x^k) / (1 - x^(k*(k+1)/2)).at n=41A280422