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A038571 Number of times n must be differentiated to reach 0. 4
0, 1, 2, 1, 3, 2, 2, 1, 4, 3, 2, 3, 3, 2, 2, 1, 5, 4, 4, 3, 3, 2, 3, 4, 4, 3, 2, 3, 3, 2, 2, 1, 6, 5, 4, 5, 4, 5, 3, 4, 4, 3, 2, 3, 3, 4, 4, 5, 5, 4, 4, 3, 3, 2, 3, 4, 4, 3, 2, 3, 3, 2, 2, 1, 7, 6, 6, 5, 4, 5, 6, 5, 4, 5, 6, 5, 3, 4, 4, 5, 5, 4, 4, 3, 3, 2, 3, 4, 4, 3, 5, 4, 5, 4, 5, 6, 6, 5, 4, 5, 4, 5, 3, 4, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

MATHEMATICA

dtn[ L_ ] := Fold[ 2#1+#2&, 0, L ]; f[ n_ ] := dtn[ Map[ Abs[ #[ [ 1 ] ]-#[ [ 2 ] ] ]&, Partition[ IntegerDigits[ n, 2 ], 2, 1 ] ] ]; g[ n_ ] := Length[ FixedPointList[ f, n ] ]-2; Table[ g[ n ], {n, 0, 120} ]

PROG

(Haskell)

a038571 n = snd $ until

   ((== 0) . fst) (\(x, i) -> (fromIntegral $ a038554 x, i + 1)) (n, 0)

-- Reinhard Zumkeller, Mar 06 2013

CROSSREFS

Cf. A038554.

Sequence in context: A284267 A296525 A175548 * A290251 A008687 A080801

Adjacent sequences:  A038568 A038569 A038570 * A038572 A038573 A038574

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Erich Friedman

STATUS

approved

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Last modified February 16 21:22 EST 2019. Contains 320199 sequences. (Running on oeis4.)