P974
projecteuler.net

Very Odd Numbers

ℹ️Published on Saturday, 13th December 2025, 04:00 pm; Solved by 345;
Difficulty level: 6

A very odd number is a number which contains only odd digits and is divisible by $105$. Further each odd digit occurs an odd number of times.

Define $\Theta (n)$ be the $n$th very odd number, then $\Theta (1) = 1117935$ and $\Theta(10^3) = 11137955115$.

Find $\Theta(10^{16})$.



Soluzione

Last modified: February 25, 2026. Website built with Franklin.jl and the lovely Julia programming language.