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A073054 Number of applications of DENEAT operator needed to reduce n to 123. 2
5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

0 does not occur. 1 first occurs for n=101, 2 first occurs for n=2, 3 first occurs for n=20, 4 first occurs for n=11, 5 first occurs for n=1. What is the least n such that a(n) > 5? - Jason Earls, Jun 03 2005

Since each string has only finitely many preimages under this map, the sequence is unbounded. Compare A100961. - N. J. A. Sloane, Jun 18 2005

REFERENCES

M. Ecker, Caution: Black Holes at Work, New Scientist (Dec. 1992)

M. J. Halm, Blackholing, Mpossibilities 69, (1999), p. 2.

LINKS

Table of n, a(n) for n=0..98.

MATHEMATICA

f[n_] := Block[{id = IntegerDigits[n]}, FromDigits[ Join[ IntegerDigits[ Length[ Select[id, EvenQ[ # ] &]]], IntegerDigits[ Length[ Select[id, OddQ[ # ] &]]], IntegerDigits[ Length[ id]] ]]]; Table[ Length[ NestWhileList[f, n, UnsameQ, All]] - 2, {n, 0, 104}] (* Robert G. Wilson v, Jun 09 2005 *)

CROSSREFS

Cf. A073053, A100961.

Sequence in context: A111129 A168464 A059688 * A072996 A244892 A278066

Adjacent sequences:  A073051 A073052 A073053 * A073055 A073056 A073057

KEYWORD

easy,nonn

AUTHOR

Michael Joseph Halm, Aug 16 2002

EXTENSIONS

Edited and corrected by Jason Earls (zevi_35711(AT)yahoo.com) and Robert G. Wilson v, Jun 03 2005

STATUS

approved

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Last modified May 23 08:43 EDT 2017. Contains 286909 sequences.