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.

A250259 The number of 4-alternating permutations of [n].

Table of values

n a(n)
0 1
1 1
2 1
3 2
4 3
5 4
6 19
7 78
8 217
9 496
10 3961
11 25442
12 105963
13 349504
14 3908059
15 34227438
16 190065457
17 819786496
18 11785687921
19 130746521282
20 907546301523
21 4835447317504
22 84965187064099
23 1141012634368398
24 9504085749177097
25 60283564499562496
26 1251854782837499881

List of values

[1, 1, 1, 2, 3, 4, 19, 78, 217, 496, 3961, 25442, 105963, 349504, 3908059, 34227438, 190065457, 819786496, 11785687921, 130746521282, 907546301523, 4835447317504, 84965187064099, 1141012634368398, 9504085749177097, 60283564499562496, 1251854782837499881]