55820

Appears in sequences

• n^2 * a(n) = 2*(17*n^2-21*n+9) * a(n-1) - 4*(112*n^2-280*n+197) * a(n-2) + 40*(68*n^2-256*n+251) * a(n-3) - 1600*(2*n-5)^2 * a(n-4), with a(0)=1, a(1)=10, a(2)=90, a(3)=780.at n=5A276020
• The number of edges formed on an isosceles triangle by straight line segments mutually connecting all vertices and all points that divide the two equal length sides into n equal parts; the base of the triangle contains no points other than its vertices.at n=18A333027