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.

A118647 a(n) is the number of binary strings of length n such that no subsequence of length 4 contains 3 or more ones.

Table of values

n a(n)
1 2
2 4
3 7
4 11
5 19
6 33
7 57
8 97
9 166
10 285
11 489
12 838
13 1436
14 2462
15 4221
16 7236
17 12404
18 21264
19 36453
20 62491
21 107127
22 183646
23 314822
24 539695
25 925191
26 1586041
27 2718927
28 4661017
29 7990313
30 13697676
31 23481725
32 40254377
33 69007488
34 118298524
35 202797424

List of values

[2, 4, 7, 11, 19, 33, 57, 97, 166, 285, 489, 838, 1436, 2462, 4221, 7236, 12404, 21264, 36453, 62491, 107127, 183646, 314822, 539695, 925191, 1586041, 2718927, 4661017, 7990313, 13697676, 23481725, 40254377, 69007488, 118298524, 202797424]

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

Content is available under The OEIS End-User License Agreement.