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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.

A309000 Number of strings of length n from a 3-symbol alphabet (A,B,C, say) containing at least one "A" and at least two "B"s.

Table of values

n a(n)
3 3
4 22
5 105
6 416
7 1491
8 5034
9 16365
10 51892
11 161799
12 498686
13 1524705
14 4635528
15 14037627
16 42391378
17 127763925
18 384536924
19 1156232175
20 3474201510
21 10434138825
22 31326533680
23 94029932643
24 282194655482
25 846802070205
26 2540859195396
27 7623517110231
28 22872497487694

List of values

[3, 22, 105, 416, 1491, 5034, 16365, 51892, 161799, 498686, 1524705, 4635528, 14037627, 42391378, 127763925, 384536924, 1156232175, 3474201510, 10434138825, 31326533680, 94029932643, 282194655482, 846802070205, 2540859195396, 7623517110231, 22872497487694]

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

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