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Search: id:A072143
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| A072143 |
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Numbers n such that 22 applications of 'Reverse and Subtract' lead to n, whereas less than 22 applications do not lead to n. |
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+0
11
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| 108811891188, 115521884478, 117611882388, 125520874479, 177781822218, 215511784488, 242351757648, 248841751158, 278882721117, 428823571176, 432244567755, 442243557756, 455663544336, 602315397684, 604405395594
(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 22 twelve-digit terms in the sequence. Further terms are obtained (a) by inserting at the center of these terms any number of 9's 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 27 2004.
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FORMULA
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n = f^22(n), n <> f^k(n) for k < 22, where f: x -> |x - reverse(x)|.
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EXAMPLE
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108811891188 -> 772386227613 -> 455663544336 -> 177781822218 -> 634446365553 -> 278882721117 -> 432244567755 -> 125520874479 -> 848957151042 -> 608805391194 -> 117611882388 -> 765676234323 -> 442243557756 -> 215511784488 -> 668975331024 ->
248841751158 -> 602315397684 -> 115521884478 -> 758966241033 -> 428823571176 -> 242351757648 -> 604405395594 -> 108811891188
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CROSSREFS
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Cf. A072137, A072140, A072141, A072142, A072718, A072719.
Adjacent sequences: A072140 A072141 A072142 this_sequence A072144 A072145 A072146
Sequence in context: A072145 A104799 A074337 this_sequence A095427 A038454 A122717
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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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