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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.

A223853 a(n) = ceiling(li(2*2^n) - li(2^n)) - (pi(2*2^n) - pi(2^n)) with li(x) the logarithmic integral and pi(x) the prime counting function.

Table of values

n a(n)
1 1
2 1
3 2
4 1
5 2
6 2
7 2
8 1
9 3
10 4
11 1
12 7
13 1
14 13
15 10
16 4
17 25
18 -5
19 49
20 17
21 38
22 82
23 103
24 -55
25 245
26 290
27 105
28 621
29 -107
30 1219
31 1196
32 -274
33 1749
34 5329
35 2881
36 2451
37 6836
38 2910
39 15905
40 28044
41 -10652
42 55758
43 18068
44 129994
45 -95925
46 52787
47 443983
48 253331
49 151395
50 740898
51 -352415

List of values

[1, 1, 2, 1, 2, 2, 2, 1, 3, 4, 1, 7, 1, 13, 10, 4, 25, -5, 49, 17, 38, 82, 103, -55, 245, 290, 105, 621, -107, 1219, 1196, -274, 1749, 5329, 2881, 2451, 6836, 2910, 15905, 28044, -10652, 55758, 18068, 129994, -95925, 52787, 443983, 253331, 151395, 740898, -352415]

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

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