

A334691


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


6



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
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OFFSET

1,2


COMMENTS

No formula is known.


LINKS

Table of n, a(n) for n=1..49.
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 colorcoded according to multiplicity.


EXAMPLE

Triangle begins:
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,
...


CROSSREFS

Cf. A255011, A331449, A334690 (row sums), A334692 (column k=2), A334693 (k=3), A334694A334699.
Sequence in context: A196102 A196099 A102409 * A128445 A097395 A108967
Adjacent sequences: A334688 A334689 A334690 * A334692 A334693 A334694


KEYWORD

nonn,tabf,more


AUTHOR

Scott R. Shannon and N. J. A. Sloane, May 18 2020


STATUS

approved



