cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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.

Original entry on oeis.org

1, 2, 2, 0, 14, 0, 0, 36, 36, 0, 0, 24, 336, 24, 0, 0, 0, 1296, 1296, 0, 0, 0, 0, 2160, 14832, 2160, 0, 0, 0, 0, 1440, 80640, 80640, 1440, 0, 0, 0, 0, 0, 233280, 1082880, 233280, 0, 0, 0, 0, 0, 0, 362880, 7776000, 7776000, 362880, 0, 0, 0, 0, 0, 0, 241920, 33264000
Offset: 1

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Author

Christian G. Bower, Jan 12 2004

Keywords

Examples

			1  2    0     0       0 ...
2  4   36    24       0 ...
0 36  336  1296    2160 ...
0 24 1296 14832   80640 ...
0  0 2160 80640 1082880 ...
		

References

  • F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, p. 113 (2.4.41).

Crossrefs

Formula

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))).