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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.

A331863 Numbers k such that R(k) - 10^floor(k/2-1) is prime, where R(k) = (10^k-1)/9 (repunit: A002275).

Table of values

n a(n)
1 8
2 12
3 17
4 20
5 24
6 42
7 1124
8 1169
9 1538
10 7902
11 27617
12 29684

List of values

[8, 12, 17, 20, 24, 42, 1124, 1169, 1538, 7902, 27617, 29684]

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

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