A072409 - OEIS

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

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OFFSET

1,2

REFERENCES

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

LINKS

Table of n, a(n) for n=1..6.

EXAMPLE

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

MATHEMATICA

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

CROSSREFS

Sequence in context: A237923 A297659 A219007 * A052455 A252619 A224461

Adjacent sequences: A072406 A072407 A072408 * A072410 A072411 A072412

KEYWORD

nonn,fini,full,base

AUTHOR

Harvey P. Dale, Jul 31 2002

EXTENSIONS

Edited by Robert G. Wilson v, Aug 09 2002

STATUS

approved