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.

A188491 Number of permutations p on the set [n] with the properties that abs(p(i)-i) <= 3 for all i, p(1) <= 3, and p(4) >= 2.

Table of values

n a(n)
0 0
1 1
2 2
3 6
4 14
5 48
6 152
7 476
8 1425
9 4340
10 13288
11 40852
12 125124
13 382888
14 1171612
15 3587505
16 10985790
17 33638142
18 102988410
19 315318756
20 965432832
21 2955964296
22 9050522241
23 27710613432
24 84843476928
25 259771465608
26 795361704776
27 2435217884992

List of values

[0, 1, 2, 6, 14, 48, 152, 476, 1425, 4340, 13288, 40852, 125124, 382888, 1171612, 3587505, 10985790, 33638142, 102988410, 315318756, 965432832, 2955964296, 9050522241, 27710613432, 84843476928, 259771465608, 795361704776, 2435217884992]

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

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