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.

A384403 a(n) is the smallest number with n digits, all of which are prime, and n prime factors, counted with multiplicity, or -1 if there is no such number.

Table of values

n a(n)
1 2
2 22
3 222
4 2223
5 22232
6 222222
7 2222325
8 22222272
9 222225552
10 2222223255
11 22222335232
12 222222327525
13 2222222372352
14 22222222575552
15 222222223327232
16 2222222225252352
17 22222222223327232
18 222222222272535552
19 2222222222225252352
20 22222222222327775232
21 222222222222737375232
22 2222222222227572375552

List of values

[2, 22, 222, 2223, 22232, 222222, 2222325, 22222272, 222225552, 2222223255, 22222335232, 222222327525, 2222222372352, 22222222575552, 222222223327232, 2222222225252352, 22222222223327232, 222222222272535552, 2222222222225252352, 22222222222327775232, 222222222222737375232, 2222222222227572375552]

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

Content is available under The OEIS End-User License Agreement.