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A160541
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Number of odd-then-even runs to reach 1 under the modified `3x+1' map: n -> n/2 if n is even, n -> (3n+1)/2 if n is odd.
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0
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0, 1, 1, 1, 1, 2, 3, 1, 4, 2, 3, 2, 2, 4, 2, 1, 3, 5, 4, 2, 1, 4, 2, 2, 5, 3, 17, 4, 4, 3, 16, 1, 6, 4, 2, 5, 4, 5, 6, 2, 17, 2, 6, 4, 4, 3, 16, 2, 5, 6, 5, 3, 2, 18, 17, 4, 7, 5, 6, 3, 3, 17, 15, 1, 6, 7, 5, 4, 3, 3, 16, 5, 18, 5, 2, 5, 5, 7, 6, 2, 4, 18, 17, 2, 1, 7, 5, 4, 6, 5, 14, 3, 3, 17, 15, 2, 19
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,6
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COMMENTS
| The 2->1 step is not counted.
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EXAMPLE
| 7->11->17->26->13->20->10->5->8->4->2->1, so the odd-then-even runs are (7->11->17->26) (13->20->10) (5->8->4->2), and a(7) is 3.
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MATHEMATICA
| Table[Length[Split[Most[NestWhileList[T, i, #!=1&]], OddQ[ #1]||EvenQ[ #2]]], {i, 1, 100}]
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CROSSREFS
| Sequence in context: A143361 A152547 A083906 * A022446 A122196 A023117
Adjacent sequences: A160538 A160539 A160540 * A160542 A160543 A160544
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KEYWORD
| nonn
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AUTHOR
| Brenton Bostick (bostick(AT)gmail.com), May 18 2009
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