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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.

A108242 a(n) is the number of coverings of 1..n by cyclic words of length 3, such that each value from 1 to n appears precisely 3 times. That is, the union of all the letters in all of the words of a given covering is the multiset {1,1,1,2,2,2,...,n,n,n}. Repeats of words are allowed in a given covering.

Table of values

n a(n)
0 1
1 1
2 2
3 16
4 256
5 7184
6 311944
7 19191448
8 1584972224
9 169021538944
10 22595033625856
11 3699135711988736
12 727774085471066752
13 169399730544125355136
14 46039989792346454771456
15 14447317177670702438831104
16 5183889091511674280049885184
17 2108937872584292649560886222848

List of values

[1, 1, 2, 16, 256, 7184, 311944, 19191448, 1584972224, 169021538944, 22595033625856, 3699135711988736, 727774085471066752, 169399730544125355136, 46039989792346454771456, 14447317177670702438831104, 5183889091511674280049885184, 2108937872584292649560886222848]

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

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