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A123260 Triangle read by rows: T(n,k) = number of specially labeled bicolored connected graphs with k points in one color class and n-k points in the other class . "Special" means there are separate labels 1,2, ...,k and 1,2, ...,n-k for the two color classes (n >= 1, k = floor((n+1)/2), ..., n).

%I A123260 #7 May 25 2017 14:46:33
%S A123260 1,1,0,1,0,5,1,0,19,1,0,205,65,1,0,1795,211,1,0,36317,14221,665,1,0,
%T A123260 636331,106819,2059,1,0,23679901,10365005,778765,6305,1,0,805351531,
%U A123260 162470155,5581315,19171,1,0,56294206205,26175881341,2495037197
%N A123260 Triangle read by rows: T(n,k) = number of specially labeled bicolored connected graphs with k points in one color class and n-k points in the other class . "Special" means there are separate labels 1,2, ...,k and 1,2, ...,n-k for the two color classes (n >= 1, k = floor((n+1)/2), ..., n).
%D A123260 R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1977.
%H A123260 R. W. Robinson, <a href="/A123260/b123260.txt">Rows 1 through 30, flattened</a>
%e A123260 The first few entries are:
%e A123260 T( 1, 0) = 1
%e A123260 T( 1, 1) = 1
%e A123260 T( 2, 0) = 0
%e A123260 T( 2, 1) = 1
%e A123260 T( 3, 0) = 0
%e A123260 T( 2, 2) = 5
%e A123260 T( 3, 1) = 1
%e A123260 T( 4, 0) = 0
%e A123260 T( 3, 2) = 19
%e A123260 T( 4, 1) = 1
%e A123260 T( 5, 0) = 0
%e A123260 T( 3, 3) = 205
%e A123260 T( 4, 2) = 65
%e A123260 T( 5, 1) = 1
%e A123260 T( 6, 0) = 0
%e A123260 1, 1;
%e A123260 0, 1, 5 ;
%e A123260 0, 1, 19, 205;
%e A123260 0, 1, 65, 1795, 36317;
%e A123260 0, 1, 211, 14221, ,...
%e A123260 0, 1, ....
%e A123260 0,
%Y A123260 Leading diagonal gives A123281. Cf. A262307.
%K A123260 nonn,tabf
%O A123260 1,6
%A A123260 _N. J. A. Sloane_, Nov 12 2006