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Search: id:A072142
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| A072142 |
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Numbers n such that 14 applications of 'Reverse and Subtract' lead to n, whereas less than 14 applications do not lead to n. |
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+0
12
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| 11436678, 13973058, 19582398, 23981958, 30581397, 32662377, 33218856, 42464466, 44664246, 48737106, 61936974, 69746193, 71064873, 76226733
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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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.
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FORMULA
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n = f^14(n), n <> f^k(n) for k < 14, where f: x -> |x - reverse(x)|.
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EXAMPLE
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11436678 -> 76226733 -> 42464466 -> 23981958 -> 61936974 -> 13973058 -> 71064873 -> 33218856 -> 32662377 -> 44664246 -> 19582398 -> 69746193 -> 30581397 -> 48737106 -> 11436678.
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CROSSREFS
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Cf. A072137, A072140, A072141, A072143, A072718, A072719.
Sequence in context: A038450 A075093 A069341 this_sequence A043674 A141281 A028241
Adjacent sequences: A072139 A072140 A072141 this_sequence A072143 A072144 A072145
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KEYWORD
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base,nonn
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AUTHOR
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Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jun 24 2002
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