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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.

A253389 a(n) is the repeating digit pattern in penultimate digit of successive powers of n (omitting initial powers without at least two digits).

Table of values

n a(n)
2 13625124998637487500
3 28428684442602686000
4 1652983470
5 2
6 31975
7 4400
8 61964512293803548770
9 8264462800
10 0
11 1234567890
12 14233809528576619047
13 16969012743858543270
14 9412305876
15 27
16 15937
17 18125674943632987050
18 2376
19 1652983470
20 0
21 24680
22 84530839221546916077
23 22644848642280060680
24 27
25 2
26 7
27 22840808842260464660
28 28556013027144398697
29 2488420660
30 0

List of values

[13625124998637487500, 28428684442602686000, 1652983470, 2, 31975, 4400, 61964512293803548770, 8264462800, 0, 1234567890, 14233809528576619047, 16969012743858543270, 9412305876, 27, 15937, 18125674943632987050, 2376, 1652983470, 0, 24680, 84530839221546916077, 22644848642280060680, 27, 2, 7, 22840808842260464660, 28556013027144398697, 2488420660, 0]

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

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