A072409 4th-order digital invariants: the sum of the 4th power of the digits of n equals some number k and the sum of the 4th power of the digits of k equals n.

1, 1634, 2178, 6514, 8208, 9474

Offset: 1

Author

Harvey P. Dale, Jul 31 2002

Keywords

• nonn
• fini
• full
• base

Examples

			2178 is included because 2^4 + 1^4 + 7^4 + 8^4 = 6514 and 6^4 + 5^4 + 1^4 + 4^4 = 2178.
		

References

• David Wells, Penguin Dictionary of Curious and Interesting Numbers, Revised Edition, London, England, 1997, p. 155&153.

Programs

Mathematica

f[n_] := Apply[Plus, IntegerDigits[Apply[Plus, IntegerDigits[n]^4]]^4]; Select[ Range[10^7], f[ # ] == # &]

Extensions

Edited by Robert G. Wilson v, Aug 09 2002