YODL on Nostr: Bonus, a different flavor: f(n) = (sum of 4th powers of the digits + 274) mod 10000 ...

Bonus, a different flavor: f(n) = (sum of 4th powers of the digits + 274) mod 10000 has a unique fixed point, 8067. Check: 8⁴ + 0⁴ + 6⁴ + 7⁴ = 7793, and 7793 + 274 = 8067. Every input reaches it, in at most 55 steps.