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.

A243828 Number A(n,k) of Dyck paths of semilength n having exactly two (possibly overlapping) occurrences of the consecutive step pattern given by the binary expansion of k, where 1=U=(1,1) and 0=D=(1,-1); square array A(n,k), n>=0, k>=0, read by antidiagonals.

Table of values

n a(n)
0 0
1 0
2 0
3 0
4 0
5 2
6 0
7 0
8 2
9 0
10 0
11 0
12 1
13 0
14 0
15 0
16 0
17 0
18 3
19 0
20 0
21 0
22 0
23 0
24 1
25 6
26 0
27 0
28 0
29 0
30 0
31 0
32 6
33 10
34 0
35 0
36 0
37 0
38 0
39 1
40 2
41 20
42 15
43 0
44 0
45 0
46 0
47 0
48 0
49 3
50 15
51 50
52 21
53 0
54 0
55 0
56 0
57 0
58 0
59 2
60 12
61 69
62 105
63 28
64 0
65 0
66 0
67 0
68 0
69 0
70 1
71 15
72 40
73 252
74 196
75 36
76 0
77 0
78 0
79 0
80 0
81 0
82 0
83 5
84 69
85 135
86 804
87 336
88 45
89 0
90 0

List of values

[0, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 0, 1, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 1, 6, 0, 0, 0, 0, 0, 0, 6, 10, 0, 0, 0, 0, 0, 1, 2, 20, 15, 0, 0, 0, 0, 0, 0, 3, 15, 50, 21, 0, 0, 0, 0, 0, 0, 2, 12, 69, 105, 28, 0, 0, 0, 0, 0, 0, 1, 15, 40, 252, 196, 36, 0, 0, 0, 0, 0, 0, 0, 5, 69, 135, 804, 336, 45, 0, 0]