cp's OEIS Frontend

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.

A056683 Numbers k such that 40*R_k + 9 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

Table of values

n a(n)
1 2
2 4
3 5
4 47
5 107
6 244
7 1043
8 20207
9 52739
10 89188

List of values

[2, 4, 5, 47, 107, 244, 1043, 20207, 52739, 89188]

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

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