Recurring Digital Invariant/4th Order/Examples/2178

Example of $4$th Order Recurring Digital Invariant

$2178$ is a $4$th order recurring digital invariant:

\(\ds 2178: \ \ \)

\(\ds 2^4 + 1^4 + 7^4 + 8^4\)

\(=\)

\(\ds 16 + 1 + 2401 + 4096\)

\(\ds = 6514\)

\(\ds 6514: \ \ \)

\(\ds 6^4 + 5^4 + 1^4 + 4^4\)

\(=\)

\(\ds 1296 + 625 + 1 + 256\)

\(\ds = 2178\)

$\blacksquare$

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $2178$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $2178$

• Weisstein, Eric W. "Recurring Digital Invariant." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/RecurringDigitalInvariant.html