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A280789 Triangle read by rows: number of topologically distinct sets of N circles with one pair touching, classified according to number of factors. 0
1, 2, 1, 6, 3, 1, 16, 10, 3, 1, 46, 30, 11, 3, 1, 128, 91, 34, 11, 3, 1, 364, 268, 108, 35, 11, 3, 1, 1029, 790, 327, 112, 35, 11, 3, 1, 2930, 2308, 992, 344, 113, 35, 11, 3, 1, 8344, 6737, 2962, 1055, 348, 113, 35, 11, 3, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

Table of n, a(n) for n=2..56.

R. J. Mathar, Topologically Distinct Sets of Non-intersecting Circles in the Plane, arXiv:1603.00077, 2016.

EXAMPLE

Triangle begins:

1,

2,1,

6,3,1,

16,10,3,1,

46,30,11,3,1,

128,91,34,11,3,1,

364,268,108,35,11,3,1,

1029,790,327,112,35,11,3,1,

...

CROSSREFS

Row sums give A269800.

Sequence in context: A059300 A321331 A046803 * A121468 A168151 A213221

Adjacent sequences:  A280786 A280787 A280788 * A280790 A280791 A280792

KEYWORD

nonn,tabl

AUTHOR

N. J. A. Sloane, Jan 20 2017

STATUS

approved

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Last modified February 19 16:02 EST 2019. Contains 320311 sequences. (Running on oeis4.)