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.

A177284 Number of permutations of 2 copies of 1..n with all adjacent differences <= 3 in absolute value.

Table of values

n a(n)
0 1
1 1
2 6
3 90
4 2520
5 41580
6 516180
7 6068622
8 76331906
9 958679970
10 11679900408
11 138047313960
12 1610654864328
13 18649754961744
14 214256589488616
15 2439692058769566
16 27562317214408488
17 309367132582535226
18 3453299423388485028
19 38354816922190327314
20 424048220090513056908

List of values

[1, 1, 6, 90, 2520, 41580, 516180, 6068622, 76331906, 958679970, 11679900408, 138047313960, 1610654864328, 18649754961744, 214256589488616, 2439692058769566, 27562317214408488, 309367132582535226, 3453299423388485028, 38354816922190327314, 424048220090513056908]

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

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