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.

A089765 Composite n whose sum of distinct divisors, s(d), ignoring divisors n and 1, divided by the count of divisors (not counting n and 1), c(d), are primes. Duplicate divisors, as in 2*2=4 are counted just once.

Table of values

n a(n)
1 4
2 8
3 9
4 18
5 21
6 25
7 33
8 49
9 57
10 69
11 81
12 85
13 93
14 121
15 129
16 133
17 145
18 169
19 177
20 205
21 213
22 217
23 237
24 249
25 253
26 265
27 273
28 289
29 309
30 361
31 393
32 417
33 445
34 469
35 489
36 493
37 505
38 517
39 529
40 553
41 565
42 573
43 597
44 633
45 669
46 685
47 697
48 753
49 777
50 781
51 793
52 813
53 817
54 841
55 865

List of values

[4, 8, 9, 18, 21, 25, 33, 49, 57, 69, 81, 85, 93, 121, 129, 133, 145, 169, 177, 205, 213, 217, 237, 249, 253, 265, 273, 289, 309, 361, 393, 417, 445, 469, 489, 493, 505, 517, 529, 553, 565, 573, 597, 633, 669, 685, 697, 753, 777, 781, 793, 813, 817, 841, 865]

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

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