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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
OFFSET
2,2
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
KEYWORD
nonn,tabl
AUTHOR
N. J. A. Sloane, Jan 20 2017
STATUS
approved