Canada numbers

Canada numbers are those $n$

such that the sum of the squares of the digits of $n$

is equal to the sum of the non-trivial divisors of $n$

, i.e. $\sigma(n)-n-1$ .

For example, 581, whose divisors are 1, 7, 83 and 581, is a Canada number because $5^2+8^2+1^2=7+83$ .

The name of these numbers is due to the fact they were defined by some mathematicians from Manitoba University to celebrate the 125th anniversary of Canada.

The Canada numbers are 125, 581, 8549, and 16999.

Pictorial representation of remainders (mod 2, 3, ...,11) frequency. For a table of values and more details click here

Useful links OEIS, Sequence A070308

Canada numbers can also be... (you may click on names or numbers)