A283824 Number of unlabeled (and unrooted) trees on n nodes having a node that is both a center and a centroid.

1, 1, 0, 1, 1, 2, 2, 6, 7, 20, 27, 83, 126

Offset

0,6

Comments

In view of the errors in the second line of the table (compare A000676 and A283823), the entries a(11)=83 and a(12)=126 should be checked carefully.

Links

Table of n, a(n) for n=0..12.

Peter Steinbach, Field Guide to Simple Graphs, Volume 1, Part 17 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.)

Peter Steinbach, Field Guide to Simple Graphs, Volume 3, Part 12 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.)

Crossrefs

Cf. A000676, A283823, A027416.

Sequence in context: A099577 A268500 A357953 * A106168 A106166 A101343

Adjacent sequences: A283821 A283822 A283823 * A283825 A283826 A283827

Keyword

nonn,more

Author

N. J. A. Sloane, Mar 19 2017

Status

approved