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A160541 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. 0
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; text; internal format)
OFFSET

1,6

COMMENTS

The 2->1 step is not counted.

LINKS

Table of n, a(n) for n=1..97.

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.

MATHEMATICA

Table[Length[Split[Most[NestWhileList[T, i, #!=1&]], OddQ[ #1]||EvenQ[ #2]]], {i, 1, 100}]

CROSSREFS

Sequence in context: A143361 A152547 A083906 * A286001 A304106 A022446

Adjacent sequences:  A160538 A160539 A160540 * A160542 A160543 A160544

KEYWORD

nonn

AUTHOR

Brenton Bostick (bostick(AT)gmail.com), May 18 2009

STATUS

approved

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Last modified April 24 04:00 EDT 2019. Contains 322406 sequences. (Running on oeis4.)