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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.

A297961 a(1) = number of 1-digit primes (that is, 4: 2,3,5,7); then a(n) = number of distinct n-digit prime numbers obtained by alternately left- and right-concatenating a digit to the a(n-1) primes obtained in the previous iteration.

Table of values

n a(n)
1 4
2 11
3 20
4 53
5 51
6 100
7 63
8 76
9 42
10 43
11 20
12 13
13 4
14 4
15 1

List of values

[4, 11, 20, 53, 51, 100, 63, 76, 42, 43, 20, 13, 4, 4, 1]

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

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