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.

A189281 Number of permutations p of 1,2,...,n satisfying p(i+2) - p(i) <> 2 for all 1 <= i <= n-2.

Table of values

n a(n)
0 1
1 1
2 2
3 5
4 18
5 75
6 410
7 2729
8 20906
9 181499
10 1763490
11 18943701
12 222822578
13 2847624899
14 39282739034
15 581701775369
16 9202313110506
17 154873904848803
18 2762800622799362
19 52071171437696453
20 1033855049655584786
21 21567640717569135515

List of values

[1, 1, 2, 5, 18, 75, 410, 2729, 20906, 181499, 1763490, 18943701, 222822578, 2847624899, 39282739034, 581701775369, 9202313110506, 154873904848803, 2762800622799362, 52071171437696453, 1033855049655584786, 21567640717569135515]

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

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