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A072142 Numbers n such that 14 applications of 'Reverse and Subtract' lead to n, whereas fewer than 14 applications do not lead to n. 21
11436678, 13973058, 19582398, 23981958, 30581397, 32662377, 33218856, 42464466, 44664246, 48737106, 61936974, 69746193, 71064873, 76226733 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

There are 14 eight-digit terms in the sequence. Further terms are obtained (a) by inserting at the center of these terms either any number of 9's (for 11436678, 32662377, 33218856, 76226733) or any number of 0's (for the other ten terms) and (b) by concatenating a term any number of times with itself and inserting an equal number of 0's at all junctures. Method (b) may be applied recursively to all terms. - Revised thanks to a comment from Hans Havermann, Jan 20 2004.

LINKS

Table of n, a(n) for n=1..14.

FORMULA

n = f^14(n), n <> f^k(n) for k < 14, where f: x -> |x - reverse(x)|.

EXAMPLE

11436678 -> 76226733 -> 42464466 -> 23981958 -> 61936974 -> 13973058 -> 71064873 -> 33218856 -> 32662377 -> 44664246 -> 19582398 -> 69746193 -> 30581397 -> 48737106 -> 11436678.

CROSSREFS

Cf. A072137, A072140, A072141, A072143, A072718, A072719.

Sequence in context: A204790 A183826 A323331 * A043674 A141281 A028241

Adjacent sequences:  A072139 A072140 A072141 * A072143 A072144 A072145

KEYWORD

base,nonn

AUTHOR

Klaus Brockhaus, Jun 24 2002

STATUS

approved

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Last modified October 17 19:24 EDT 2019. Contains 328127 sequences. (Running on oeis4.)