|
Search: id:A072719
|
|
|
| A072719 |
|
Numbers n such that 17 applications of 'Reverse and Subtract' lead to n, whereas less than 17 applications do not lead to n. |
|
+0
8
|
|
| 1186781188132188, 1464465185355348, 2178772178212278, 2191191178088088, 2196702178032978, 2202202177977978, 2334334176656658, 3041250269587497, 4361064356389356, 4906609350933906, 6232232537677674, 6543356534566434
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
There are 17 sixteen-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.
This is a working sequence. It is neither by computation nor by proof guaranteed that there are no smaller or interleaved terms.
|
|
FORMULA
|
n = f^17(n), n <> f^k(n) for k < 17, where f: x -> |x - reverse(x)|.
|
|
EXAMPLE
|
1186781188132188 -> 7625537623744623 -> 4361064356389356 -> 2178772178212278 -> 6543356534566434 -> 2196702178032978 -> 6595606534043934 -> 2202202177977978 -> 6595595534044044 -> 2191191178088088 -> 6617617533823824 -> 2334334176656658 ->
6232232537677674 -> 1464465185355348 -> 6971070630289293 -> 3041250269587497 -> 4906609350933906 -> 1186781188132188.
|
|
CROSSREFS
|
Cf. A072137, A072141, A072142, A072143, A072718.
Sequence in context: A128446 A052098 A095431 this_sequence A134692 A098099 A067495
Adjacent sequences: A072716 A072717 A072718 this_sequence A072720 A072721 A072722
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jul 15 2002
|
|
|
Search completed in 0.002 seconds
|
