A334691 - OEIS

A334691

Irregular triangle read by rows: T(n,k) (n >= 1, 2 <= k <= 2*n) = number of interior vertices in the n-th figure shown in A255011 (meaning the figure with 4n points on the perimeter) where k lines meet.

1, 20, 8, 1, 204, 32, 8, 0, 1, 616, 152, 20, 8, 4, 0, 1, 2428, 252, 36, 16, 4, 0, 0, 0, 1, 3968, 572, 156, 72, 16, 8, 4, 0, 4, 0, 1, 11164, 900, 120, 52, 16, 8, 4, 0, 0, 0, 0, 0, 1, 16884, 1712, 396, 132, 40, 20, 8, 8, 8, 0, 0, 0, 0, 0, 1, 30116, 2536, 600, 140, 60, 24, 8, 20, 8, 0, 0, 0, 0, 0, 0, 0, 1

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

No formula is known.

LINKS

Table of n, a(n) for n=1..81.

Scott R. Shannon, Data for triangles A334691 and A334699

Scott R. Shannon, Colored illustration for n = 2

Scott R. Shannon, Illustration for n=3 showing interior vertices color-coded according to multiplicity.

EXAMPLE

Triangle begins: