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.

A000250 Number of symmetric reflexive relations on n nodes: (1/2)*A000666.

Table of values

n a(n)
1 1
2 3
3 10
4 45
5 272
6 2548
7 39632
8 1104306
9 56871880
10 5463113568
11 978181717680
12 326167542296048
13 202701136710498400
14 235284321080559981952
15 511531711735594715527360
16 2089424601541011618029114896
17 16084004145036771186002041099712
18 234026948449058790311618594954430848
19 6454432593140577452393525511509194184320

List of values

[1, 3, 10, 45, 272, 2548, 39632, 1104306, 56871880, 5463113568, 978181717680, 326167542296048, 202701136710498400, 235284321080559981952, 511531711735594715527360, 2089424601541011618029114896, 16084004145036771186002041099712, 234026948449058790311618594954430848, 6454432593140577452393525511509194184320]

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

Content is available under The OEIS End-User License Agreement.