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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.

A281922 Consider a string of n 1. From left to right for any couple of consecutive numbers apply the transform 11 -> 10, 10 -> 11, 00 -> 00, 01 -> 01. At any further step restart the process considering the value of the rightmost digit as input to the leftmost one to apply the transform again. Sequence gives the number of steps necessary to reach again a string of n 1 or -1 if such a number does not exist.

Table of values

n a(n)
2 2
3 5
4 4
5 17
6 -1
7 109
8 8
9 65
10 89
11 1115
12 -1
13 7297
14 2531
15 4369
16 16
17 257
18 155174
19 195814
20 495146
21 5201
22 1334551
23 1725452
24 1485482
25 -1
26 -1
27 -1
28 17256565
29 277691849
30 6145997
31 2029501
32 32
33 1025
34 67672804
35 1157011598
36 12054050100
37 22287270331
38 15597512810
39 -1

List of values

[2, 5, 4, 17, -1, 109, 8, 65, 89, 1115, -1, 7297, 2531, 4369, 16, 257, 155174, 195814, 495146, 5201, 1334551, 1725452, 1485482, -1, -1, -1, 17256565, 277691849, 6145997, 2029501, 32, 1025, 67672804, 1157011598, 12054050100, 22287270331, 15597512810, -1]

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

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