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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.

A369397 Number of binary relations R on [n] such that the (unique) idempotent in {R,R^2,R^3,...} is an equivalence relation.

Table of values

n a(n)
0 1
1 1
2 5
3 157
4 26345
5 18218521
6 47136254765
7 451286947588597
8 16264532016440908625
9 2253156851039460378774961
10 1219026648017155982267265596885
11 2601923405098893502520360223043594957
12 22040885615442635622424409144799379027505465

List of values

[1, 1, 5, 157, 26345, 18218521, 47136254765, 451286947588597, 16264532016440908625, 2253156851039460378774961, 1219026648017155982267265596885, 2601923405098893502520360223043594957, 22040885615442635622424409144799379027505465]

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

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