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A072409
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4th order digital invariants: the sum of the 4th power of the integer digits of n equals some number k and the sum of the 4th power of the integer digits of k equals n.
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3
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OFFSET
| 1,2
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REFERENCES
| David Wells, Penguin Dictionary of Curious and Interesting Numbers, Revised Edition, London, England, 1997, p. 155&153.
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EXAMPLE
| 2178 is included because 2^4 + 1^4 + 7^4 + 8^4 = 6514 and 6^4 + 5^4 + 1^4 + 4^4 = 2178.
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MATHEMATICA
| f[n_] := Apply[Plus, IntegerDigits[Apply[Plus, IntegerDigits[n]^4]]^4]; Select[ Range[10^7], f[ # ] == # &]
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CROSSREFS
| Sequence in context: A198510 A202985 A063891 * A052455 A054808 A206234
Adjacent sequences: A072406 A072407 A072408 * A072410 A072411 A072412
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KEYWORD
| nonn,fini,full,base
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AUTHOR
| Harvey P. Dale (hpd1(AT)nyu.edu), Jul 31 2002
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EXTENSIONS
| Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 09 2002
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