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.

A086673 Number of right-truncatable semiprimes <= n.

Table of values

n a(n)
1 0
2 0
3 0
4 1
5 1
6 2
7 2
8 2
9 3
10 3
11 3
12 3
13 3
14 3
15 3
16 3
17 3
18 3
19 3
20 3
21 3
22 3
23 3
24 3
25 3
26 3
27 3
28 3
29 3
30 3
31 3
32 3
33 3
34 3
35 3
36 3
37 3
38 3
39 3
40 3
41 3
42 3
43 3
44 3
45 3
46 4
47 4
48 4
49 5
50 5
51 5
52 5
53 5
54 5
55 5
56 5
57 5
58 5
59 5
60 5
61 5
62 6
63 6
64 6
65 7
66 7
67 7
68 7
69 8
70 8
71 8
72 8
73 8
74 8
75 8
76 8
77 8
78 8
79 8
80 8
81 8
82 8
83 8
84 8
85 8
86 8
87 8
88 8
89 8
90 8
91 9
92 9
93 10
94 11
95 12
96 12
97 12
98 12

List of values

[0, 0, 0, 1, 1, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 10, 11, 12, 12, 12, 12]