A275923 Number of connected arrangements of n circles in the affine plane, in the sense that the union of the solid circles is a connected set.

1, 1, 2, 11, 156, 16756

Offset

0,3

Comments

Arrangements in A250001 that are connected (in the sense that the union of the solid circles is a connected set). See A250001, the main entry for this problem, for further information.

Is this also 1 together with column 1 of A285996? - Omar E. Pol, May 28 2017

Links

Table of n, a(n) for n=0..5.

Jon Wild, Figure showing relationship between A250001, A275923, A275924, and A288554 for n=3 circles

Crossrefs

Cf. A250001, A275924, A288554-A288568.

Sequence in context: A143875 A245054 A058154 * A288560 A318173 A349639

Adjacent sequences: A275920 A275921 A275922 * A275924 A275925 A275926

Keyword

nonn,more

Author

N. J. A. Sloane, Aug 29 2016, based on information supplied by Jon Wild.

Extensions

a(5) from Jon Wild, Aug 31 2016

Status

approved