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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.

A260509 Number of graphs on labeled vertices {x, y, 1, 2, ..., n}, such that there is a partition of the vertices into V_1 and V_2 with x in V_1, y in V_2, every v in V_1 adjacent to an even number of vertices in V_2, and every v in V_2 adjacent to an even number of vertices in V_1.

Table of values

n a(n)
0 1
1 3
2 23
3 351
4 11119
5 703887
6 89872847
7 22945886799
8 11740984910671
9 12014755220129103
10 24602393557227030863
11 100754627840184914661711
12 825349838279823049359417679
13 13521969078301639826644261077327
14 443083578482642171171990600910324047
15 29037623349739387300519333731237743018319

List of values

[1, 3, 23, 351, 11119, 703887, 89872847, 22945886799, 11740984910671, 12014755220129103, 24602393557227030863, 100754627840184914661711, 825349838279823049359417679, 13521969078301639826644261077327, 443083578482642171171990600910324047, 29037623349739387300519333731237743018319]

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

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