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.

A193641 Number of arrays of -1..1 integers x(1..n) with every x(i) in a subsequence of length 1 or 2 with sum zero.

Table of values

n a(n)
1 1
2 3
3 7
4 15
5 33
6 73
7 161
8 355
9 783
10 1727
11 3809
12 8401
13 18529
14 40867
15 90135
16 198799
17 438465
18 967065
19 2132929
20 4704323
21 10375711
22 22884351
23 50473025
24 111321761
25 245527873
26 541528771
27 1194379303
28 2634286479
29 5810101729
30 12814582761

List of values

[1, 3, 7, 15, 33, 73, 161, 355, 783, 1727, 3809, 8401, 18529, 40867, 90135, 198799, 438465, 967065, 2132929, 4704323, 10375711, 22884351, 50473025, 111321761, 245527873, 541528771, 1194379303, 2634286479, 5810101729, 12814582761]