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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.

A071711 Let s(k) denote the k-th term of an integer sequence such that s(0)=0 and s(i) for all i>0 is the least natural number such that no four elements of {s(0),..,s(i)} are in arithmetic progression. Then it appears that there are many set of 3 consecutive integers in s(k). Sequence gives the smallest element in those triples.

Table of values

n a(n)
1 0
2 7
3 14
4 28
5 48
6 55
7 64
8 86
9 108
10 168
11 286
12 371
13 471
14 633
15 760
16 982
17 1032
18 1136
19 1261
20 1600
21 1739
22 1788
23 1822
24 1848
25 3832
26 4225
27 5504
28 7729
29 8062
30 9229
31 10110
32 21977
33 27953
34 39335
35 50820
36 50852
37 86357
38 95586
39 106331
40 160418
41 295806
42 314853
43 368358
44 459825

List of values

[0, 7, 14, 28, 48, 55, 64, 86, 108, 168, 286, 371, 471, 633, 760, 982, 1032, 1136, 1261, 1600, 1739, 1788, 1822, 1848, 3832, 4225, 5504, 7729, 8062, 9229, 10110, 21977, 27953, 39335, 50820, 50852, 86357, 95586, 106331, 160418, 295806, 314853, 368358, 459825]

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

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