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A274818 Triangle read by rows: T(n,k) = total number of regions in all arrangements of n circles in the affine plane forming k regions, including the regions that do not belong to the circles. 4
1, 0, 4, 3, 0, 0, 12, 16, 10, 0, 28, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Consider the arrangements of n circles described in A250001.

LINKS

Table of n, a(n) for n=1..14.

FORMULA

T(n,k) = k*A274776(n,k).

EXAMPLE

Triangle begins:

1;

0, 4,  3;

0, 0, 12, 16, 10, 0, 28;

0, 0,  0, ...

...

For n = 3 and k = 5 there are 2 arrangements of 3 circles in the affine plane forming 5 regions, including the regions that do not belong to the circles, so T(3,5) = 2*5 = 10.

For n = 3 and k = 6 there are no arrangements of 3 circles in the affine plane forming 6 regions, including the regions that do not belong to the circles, so T(3,6) = 0*5 = 0.

Of course, there is a right triangle of all zeros starting from the second row.

CROSSREFS

Row sums give A274822.

First differs from A274819 at a(10).

Cf. A250001, A274776.

Sequence in context: A019983 A019984 A187765 * A274819 A106646 A056969

Adjacent sequences:  A274815 A274816 A274817 * A274819 A274820 A274821

KEYWORD

nonn,tabf,hard,more

AUTHOR

Omar E. Pol, Jul 07 2016

STATUS

approved

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Last modified February 21 22:56 EST 2018. Contains 299427 sequences. (Running on oeis4.)