126711

Appears in sequences

• a(n) = index of the triangular number A076971(n).at n=32A076972
• The Wiener index of the linear phenylene with n hexagons.at n=18A224454
• a(n) = Sum_{1 <= x_1, x_2, x_3 <= n} gcd(x_1, x_2, x_3, n)^5.at n=9A372930