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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.

A271219 Number n of antichains of P(En) x En*, ordered by lexicographic order, with En a poset of n elements with no pair of elements ordered, and with En* that same set augmented with an (n+1)th element smaller than all others.

Table of values

n a(n)
0 1
1 5
2 83
3 28925
4 7663696588

List of values

[1, 5, 83, 28925, 7663696588]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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