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A039637 Number of steps to fixed point of "n -> n/2 or (n+1)/2 until result is prime". 5
1, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 4, 4, 1, 3, 1, 3, 2, 2, 1, 4, 2, 2, 3, 3, 1, 5, 1, 5, 2, 2, 4, 4, 1, 2, 4, 4, 1, 3, 1, 3, 2, 2, 1, 5, 3, 3, 3, 3, 1, 4, 4, 4, 2, 2, 1, 6, 1, 2, 6, 6, 3, 3, 1, 3, 5, 5, 1, 5, 1, 2, 3, 3, 5, 5, 1, 5, 2, 2, 1, 4, 2, 2, 4, 4, 1, 3, 3, 3, 2, 2, 6, 6, 1, 4, 4, 4, 1, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

MATHEMATICA

upplist[ n_Integer ] := Length/@Drop[ FixedPointList[ If[ EvenQ[ # ]&&#>2, #/ 2, If[ PrimeQ[ # ]||(#===1), #, (#+1)/2 ] ]&, n, 20 ], -1 ]

PROG

(Haskell)

a039637 1 = 1

a039637 n = snd $ until ((== 1) . a010051 . fst)

                        (\(x, i) -> ((x + 1) `div` 2 , i + 1)) (n, 1)

-- Reinhard Zumkeller, Nov 17 2013

CROSSREFS

Cf. A039634-A039645.

Cf. A010051, A039635, A039636, A039644, A039645.

Sequence in context: A323436 A056692 A331600 * A194548 A274009 A069157

Adjacent sequences:  A039634 A039635 A039636 * A039638 A039639 A039640

KEYWORD

nonn

AUTHOR

Wouter Meeussen

EXTENSIONS

Offset corrected by Reinhard Zumkeller, Nov 17 2013

STATUS

approved

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Last modified July 28 19:33 EDT 2021. Contains 346335 sequences. (Running on oeis4.)