A subset the arrangements of n circles described in A250001, which is the main entry for this sequence.
See also the comments related to A000081 from Benoit Jubin and N. J. A. Sloane in A250001.
Table of n, a(n) for n=0..4.
a(n) = A250001(n) - A000081(n+1).
Row sums of A261070 except its column k = 0.
Cf. A000081, A250001.
Sequence in context: A190903 A303486 A064747 * A278096 A272499 A305604
Adjacent sequences: A285992 A285993 A285994 * A285996 A285997 A285998
Omar E. Pol, May 17 2017