A176357 Partial sums of A036403.

1, 127, 4054, 37210, 134325, 776241, 1313848, 5536128, 7280823, 28243653, 32246894, 74873810

Offset: 1

Author

Jonathan Vos Post, Apr 15 2010

Keywords

• nonn
• more

Comments

Partial sums of number of equilateral triangles whose vertices (whether connected by lines or not) lie at intersection points resulting from drawing lines connecting every pair of vertices of a regular 3n-gon (and extending beyond the polygon).

Examples

			a(4) = 1 + 126 + 3927 + 33156 = 37210 = 2 * 5 * 61^2.
		

Crossrefs

Cf. A006600, A036403.

Formula

a(n) = Sum_{i=1..n} A036403(i).