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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.

A220687 Number of ways to reciprocally link elements of an nX7 array either to themselves or to exactly two horizontal, vertical or antidiagonal neighbors.

Table of values

n a(n)
1 1
2 1081
3 362057
4 128995678
5 42362190063
6 14108684022136
7 4701615485821782
8 1566852499542855296
9 522108399243273023731
10 173978947909208417520148
11 57974051497341052095013087
12 19318375776055542860988503113

List of values

[1, 1081, 362057, 128995678, 42362190063, 14108684022136, 4701615485821782, 1566852499542855296, 522108399243273023731, 173978947909208417520148, 57974051497341052095013087, 19318375776055542860988503113]

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

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