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A249752
Triangle read by rows: T(n,k) = number of arrangements of n circles in the affine plane having k outer circles.
7
1, 1, 2, 3, 5, 6, 14, 52, 60, 47
OFFSET
1,3
COMMENTS
Consider the arrangements of n circles described in A250001.
T(n,k) is the number of arrangements of n circles in the affine plane whose perimeters are formed with parts from k circles. - Omar E. Pol, Aug 09 2015
From Omar E. Pol, Jul 06 2016: (Start)
Observation 1: column 1 gives A250001, at least if 1<=n<=4.
Observation 2: sum of n-th row = T(n+1,1), at least if 1<=n<=3. (End)
EXAMPLE
Triangle begins:
1;
1, 2;
3, 5, 6;
14, 52, 60, 47;
...
CROSSREFS
Sum of n-th row = A250001(n).
Leading diagonal gives A274702.
Sequence in context: A131825 A289124 A304297 * A222313 A355483 A079226
KEYWORD
nonn,tabl,hard,more
AUTHOR
Omar E. Pol, Dec 14 2014
EXTENSIONS
Corrected a(5)-a(6) and added a(7)-a(10) from Omar E. Pol, Oct 13 2015
STATUS
approved