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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.

A218394 Numbers such that sum(i<=n) binomial(n,i)*binomial(2*n-2*i, n-i) is not divisible by 5.

Table of values

n a(n)
1 1
2 5
3 7
4 11
5 25
6 27
7 31
8 35
9 37
10 51
11 55
12 57
13 61
14 125
15 127
16 131
17 135
18 137
19 151
20 155
21 157
22 161
23 175
24 177
25 181
26 185
27 187
28 251
29 255
30 257
31 261
32 275
33 277
34 281
35 285
36 287
37 301
38 305
39 307
40 311
41 625
42 627
43 631
44 635
45 637
46 651
47 655
48 657
49 661
50 675
51 677
52 681
53 685
54 687
55 751

List of values

[1, 5, 7, 11, 25, 27, 31, 35, 37, 51, 55, 57, 61, 125, 127, 131, 135, 137, 151, 155, 157, 161, 175, 177, 181, 185, 187, 251, 255, 257, 261, 275, 277, 281, 285, 287, 301, 305, 307, 311, 625, 627, 631, 635, 637, 651, 655, 657, 661, 675, 677, 681, 685, 687, 751]

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

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