A176357 Partial sums of A036403.

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

Offset

1,2

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).

Links

Table of n, a(n) for n=1..12.

Formula

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

Example

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

Crossrefs

Cf. A006600, A036403.

Sequence in context: A144969 A114535 A215611 * A201071 A137789 A268663

Adjacent sequences: A176354 A176355 A176356 * A176358 A176359 A176360

Keyword

nonn,more

Author

Jonathan Vos Post, Apr 15 2010

Status

approved