cp's OEIS Frontend

A091466 Table (by antidiagonals) of labeled alternating octopuses with n black nodes and k white nodes. Each type of object labeled from its own label set.

%I A091466 #6 Sep 05 2025 00:22:29
%S A091466 1,2,2,0,14,0,0,36,36,0,0,24,336,24,0,0,0,1296,1296,0,0,0,0,2160,
%T A091466 14832,2160,0,0,0,0,1440,80640,80640,1440,0,0,0,0,0,233280,1082880,
%U A091466 233280,0,0,0,0,0,0,362880,7776000,7776000,362880,0,0,0,0,0,0,241920,33264000
%N A091466 Table (by antidiagonals) of labeled alternating octopuses with n black nodes and k white nodes. Each type of object labeled from its own label set.
%D A091466 F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, p. 113 (2.4.41).
%F A091466 Double e.g.f.: A(x, y) = Sum_{i, j>=0} (x^i*y^j/(i!*j!)) = log((1-x*y)^2/(1-x*y*(3+x+y))).
%e A091466 1  2    0     0       0 ...
%e A091466 2  4   36    24       0 ...
%e A091466 0 36  336  1296    2160 ...
%e A091466 0 24 1296 14832   80640 ...
%e A091466 0  0 2160 80640 1082880 ...
%Y A091466 Cf. A029767, A091467.
%K A091466 nonn,tabl,changed
%O A091466 1,2
%A A091466 _Christian G. Bower_, Jan 12 2004