Overview

A database with every combination of prime factors (2,3 and 7) that produce a multiplicative persistence > 2 in base 10 (that i've found so far).

Description

Multiple numbers may multiply to a common combination of prime factors, for example 277 and 772 both multiply to 98 (2*7*7). So to reduce search space we look for the combinations itself. For short a combination is written as 2^i * 3^j * 7^k .

Why no 5's?

5's are evil!

Test

I've missed a combination? Test it here and it will be automatically inserted in the database (if missing).

2^ A valid number between 0 and 10000 is required. 3^ A valid number between 0 and 10000 is required. 7^ A valid number between 0 and 10000 is required. Persistence Test Toggle Dropdown Show expansion

The database

Count: 8787

Checked: i, j, k <= 2455

Combination Persistence