A283824 - OEIS

%I #7 Mar 19 2017 14:02:57

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

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

%C 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.

%H Peter Steinbach, <a href="/A000088/a000088_17.pdf">Field Guide to Simple Graphs, Volume 1</a>, Part 17 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.)

%H Peter Steinbach, <a href="/A000055/a000055_12.pdf">Field Guide to Simple Graphs, Volume 3</a>, Part 12 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.)

%Y Cf. A000676, A283823, A027416.

%K nonn,more

%O 0,6

%A _N. J. A. Sloane_, Mar 19 2017