A281348 - OEIS

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A281348

Triangle read by rows: number of topologies of n nested circles intersecting at most as binaries, according to number of factors.

1

1, 2, 1, 5, 2, 1, 16, 8, 2, 1, 53, 26, 8, 2, 1, 189, 100, 30, 8, 2, 1, 694, 375, 115, 30, 8, 2, 1, 2642, 1473, 453, 120, 30, 8, 2, 1, 10270, 5823, 1827, 473, 120, 30, 8, 2, 1, 40747, 23479, 7432, 1936, 479, 120, 30, 8, 2, 1, 164033, 95618, 30622, 7954, 1961, 479, 120, 30, 8, 2, 1

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..66.

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

EXAMPLE

Triangle begins:

1,

2,1,

5,2,1,

16,8,2,1,

53,26,8,2,1,

189,100,30,8,2,1,

694,375,115,30,8,2,1,

2642,1473,453,120,30,8,2,1,

10270,5823,1827,473,120,30,8,2,1,

...

CROSSREFS

Row sums give A281347.

Sequence in context: A048494 A047848 A275431 * A371305 A308698 A308569

Adjacent sequences: A281345 A281346 A281347 * A281349 A281350 A281351

KEYWORD

nonn,tabl

AUTHOR

N. J. A. Sloane, Jan 20 2017

STATUS

approved