cp's OEIS Frontend

A283826 Irregular triangle read by rows: T(n,k) = number of trees on n nodes with radius k, n>=1, 1 <= k <= floor(n/2).

%I A283826 #17 Apr 03 2017 04:13:14
%S A283826 0,1,1,1,1,1,2,1,4,1,1,7,3,1,11,10,1,1,17,25,4,1,25,61,18,1,1,36,132,
%T A283826 61,5,1,50,277,194,28,1,1,70,554,553,117,6,1,94,1077,1495,451,40,1,1,
%U A283826 127,2034,3823,1552,197,7,1,168,3770,9427,5020,879,54,1,1,222,6853,22466,15289,3485,305,8,1
%N A283826 Irregular triangle read by rows: T(n,k) = number of trees on n nodes with radius k, n>=1, 1 <= k <= floor(n/2).
%C A283826 The radius of a tree is the maximal distance of a node from the center.
%H A283826 Peter Steinbach, <a href="/A000055/a000055_8.pdf">Field Guide to Simple Graphs, Volume 3</a>, Part 8 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.)
%F A283826 T(n,k) = A034853(n,2k-1) + A034853(n,2k). - _R. J. Mathar_, Apr 03 2017
%e A283826 Triangle begins:
%e A283826   0,
%e A283826   1,
%e A283826   1,
%e A283826   1,  1,
%e A283826   1,  2,
%e A283826   1,  4,   1,
%e A283826   1,  7,   3,
%e A283826   1, 11,  10,   1,
%e A283826   1, 17,  25,   4,
%e A283826   1, 25,  61,  18,  1,
%e A283826   1, 36, 132,  61,  5,
%e A283826   1, 50, 277, 194, 28, 1,
%e A283826   ...
%Y A283826 Cf. A283827.
%Y A283826 See also A000676, A000677, A027416, A102911, A004250 (column 2?), A000055 (row sums).
%K A283826 nonn,tabf
%O A283826 1,7
%A A283826 _N. J. A. Sloane_, Mar 19 2017