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.

A243874 Number of Dyck paths of semilength n having exactly 4 (possibly overlapping) occurrences of the consecutive steps UDUUUDDDUD (with U=(1,1), D=(1,-1)).

Table of values

n a(n)
17 1
18 6
19 31
20 156
21 766
22 3717
23 17812
24 84342
25 395152
26 1833853
27 8438976
28 38540936
29 174819086
30 788082431
31 3532770025
32 15755543925
33 69937932805
34 309113716505
35 1360804143915
36 5968626187120
37 26089764842864
38 113680654898844
39 493874661384094
40 2139660006480909

List of values

[1, 6, 31, 156, 766, 3717, 17812, 84342, 395152, 1833853, 8438976, 38540936, 174819086, 788082431, 3532770025, 15755543925, 69937932805, 309113716505, 1360804143915, 5968626187120, 26089764842864, 113680654898844, 493874661384094, 2139660006480909]

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

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