229791

Appears in sequences

• G.f. A(x) satisfies A(x) = 1 + x/(1+x^3)^2 * A(x)^3.at n=9A390172
• a(n) is the number of 5 element sets of distinct integer-sided trapezoids whose base angles are 60 degrees that fill an equilateral triangular grid of side n units with a trapezoid filled by 3 trapezoids.at n=47A391204